In this case I didn't tell the guy, I just kept looking. He is a very good and tricky player - maybe just a little distracted or drunk that day. He was playing unusually tight so it only really became a factor in two hands:
1) He raised preflop with KT, I have AT - flop came out 52K and he bet so I lost the $7 preflop call I might not have made otherwise.
2) He folded two diamonds, flop gave me two pair with two diamonds showing and I had one - I figured it would be a good chance to milk another 2 players trying to hit a flush draw, but a third diamond came on the turn. What are the freakin odds
Part of it was I was too busy making sure nobody saw me looking (forgot my sunglasses) and trying to adjust my odds calculations to really concentrate on the hands. I guess I just need more practice