I saw this spot a lot when I was at 5NL. Check and use his bet size (if he bets) as a read. I have noticed that at those stakes people bet half the pot or less when they don't have the ace, and bet 3/4-pot-or shove when they do. If he checks bet out 3/4 on the turn. This worked great for me.. I was almost always right with this read.

Your average fish at this level does not understand nor vary their bet sizes. They play their cards and nothing more.. when confident in their hand they bet more.. this is only on average, and this is all we should be concerned with.. being right more than 50% of the time is +ev.