[Gamblor]

If you made pot sized raise on flop, you would just have one pot sized bet on the turn and you would already be all-in and not having to worry about folding the best hand here.

I made the smallish raise to either:

1) induce a reraise all in for value, or
2) to build a pot should I hit, or
3) to give myself a chance to check behind should I miss the turn.

I didn't want to lose him right away, and I didn't want to build such a pot that if he does just call and fire the turn, I won't be forced to call off my stack.