Pretty standard play there. Shorty with 88 has to shove on the button, SB might have shoved, but I see his thinking, and you made what I think was a proper call. You were getting pretty good odds
with a pretty good hand. Once you didn't bet the flop, SB felt u didn't have a K, and shoved just to get you out of the pot.
Good fold, on a standard hand.
There are a lot of folks who would say re-shoving pre is the proper play. I am not one of them. With AJ, you're only gonna get called by a better hand. There is no need for it. You, being last to act, have the luxury of seeing a valuable flop, reasonably cheap. Be satisfied with that in these situations.
If you hit the flop big, THEN you get to continue.
IMHO, you did everything right.