Is my HU play flawed at SNGs?

[DougI]

When I get to the final 2 at an SNG, I am usually very aggressive with PP unless I am the large stack and want to trap.

There are situations that happen a lot in HU play, and I can sense what will happen more often than not when I push all-in (a classic coin flip or close to coin flip race).

The scenario is this:
My opponent and I have about the same amount of chips. The opponent raises me about 1/3 of my chips. I am staring down at PP 77, 88, or 99.

Do I call, re-raise to 1/2 his chips, or go all-in?

I find that I am very aggressive and tend to go all-in when I sense the opponent is probably playing Ax.
Is this too aggressive? Should I wait for the flop to see if all is clear with Aces and then go all-in?

What is your course of action?