Villian Stats (VPIP/PFR/AF): 30.1/20.3/29.7

NL Holdem 0.05(BB)
BTN ($6.33) [VPIP: 30.1% | PFR: 20.3% | AGG: 29.7% | Flop Agg: 32.7% | Turn Agg: 36% | River Agg: 11.8% | 3-Bet: 10.9% | 4-Bet: 0% | Cold Call: 21.1% | Hands: 241]
SB ($4.95) [VPIP: 30.8% | PFR: 7.7% | AGG: 75% | Hands: 13]
BB ($4.51) [VPIP: 25.2% | PFR: 18.8% | AGG: 25.3% | Hands: 433]
UTG ($9.26) [VPIP: 32.5% | PFR: 21.7% | AGG: 25.4% | Hands: 311]
HERO ($5.07) [VPIP: 20.6% | PFR: 13.9% | AGG: 31% | Flop Agg: 33.2% | Turn Agg: 31.6% | River Agg: 24.8% | 3-Bet: 5.9% | Fold to 3-Bet: 51.9% | 4-Bet: 7.3% | Hands: 9847]
CO ($4.82) [VPIP: 28.3% | PFR: 15.1% | AGG: 28% | Hands: 57]

Dealt to Hero: A♦ A♠

UTG Raises To $0.10, HERO Raises To $0.40, CO Folds, BTN Calls $0.40, SB Folds, BB Folds, UTG Folds

Hero SPR on Flop: [4.81 effective]
Flop ($0.97): K♠ 5♣ 4♠
HERO Bets $0.50 (Rem. Stack: $4.17), BTN Calls $0.50 (Rem. Stack: $5.43)

Turn ($1.97): K♠ 5♣ 4♠ K♣
HERO Checks, BTN Checks

River ($1.97): K♠ 5♣ 4♠ K♣ Q♦
HERO Bets $1.25 (Rem. Stack: $2.92), BTN Raises To $5.43 (allin), HERO Folds

Spoiler alert!

Click to Reveal!

BTN wins: $4.25

I was actually about to make a reluctant call when I timed out. I wanted to put it up though and see if next time I should just snap it off. It feels a lot like a Kx of spades or QQ. My problem is what cold calls a 3 bet and calls the flop. QQ seems like a loose call post but it is the micros. Kx of Spades on the other hand is very much encouraged to call.

Was I being too nitty here?

Hello, it was very hard decision on the river. I don't think so that opponent play call your 3bet pre flop with QQ, because it is very strong hand and on micro limit players should play 4bet with QQ. As you played - you played bets for over 60% of the pot on the flop and here it is fine. On the turn - it seems that you played also fine, but when you check on the turn you give for your opponent initiative. When opponent raised you on the river it seems very strong, and it seems that he played slowplay with something on the turn, his check on the turn can means that he can excpect any bet from you on the river. So in conlusion IMO I think that you didn't make a big mistake with fold on the river with pocket AA. GL

After check, check on the turn, I think check/call a reasonable bet on the river would be a good alternative line.

Preflop
Standard 3-bet, and I like your sizing going 4X against a min-open.

Flop
Standard C-bet. Maybe you can size down a bit but half pot is definitely not terrible at 5NL for a 3-bet pot.

Turn
Not the greatest card obviously, but if we did not do it already on the flop, now its time to stop for a moment and think about, what kind of range range he cold called our 3-bet with. He is not a fish but more one of those bad regs with a slightly to high VPIP and to much gap between VPIP and PFR, so I think, he has a pretty good hand, when he does this.

Probably not AA or KK, but something like TT-QQ, AK or AQs, and that is probably just about it. With AA in your hand and with KK on the board he can only have 4 combos of AK now, but he can still have 18 combos of TT-QQ. And I think, TT-QQ will call another small bet, so I prefer to bet again for value. Maybe something like 40% pot. Give him a price he cant resist.

River
Given the range I just put him on, this was the worst card, that could possibly have hit. Not only did his QQ get there, but its also a scare card to JJ and TT, so I think, you need to check now and then make a decision, if he bet. And when you get raised all in, this is a snap fold to me.

Checking back turn and then raising river is a line, people almost never take as a bluff, because it makes no sense. When we are bluffing, we want to attack weakness, and you showed weakness on the turn but strenght on the river. Also busted draws do not matter, because with his narrow range he dont have any. He could have a hand like AcQc, but even that made a pair on the river. So for him to even have a bluff, he would need to be turning JJ or TT into a bluff, which is a very advanced play, you just dont see much at 5NL.

On the other hand it makes perfect sense for him to play like this with QQ. So even though I hate narrowing my opponent down to just one hand, in this case I will stick my neck out and say, he almost certainly had QQ and got there on the river. Sucks for you but at least you did not pay him off with your entire stack.