Oh please. Candidates say hundreds of things on the campaign trail every day. Who can remember perfectly something that happened 12 years ago, anyway?
I can't perfectly remember every field trip I took in 6th grade, but I most certainly do remember that I was not under gunfire during any of them.
Coming under fire in that way is not the same as coming under fire when you're walking down the street. You might not even notice it unless someone tells you, even if you have to take precautions like 'keeping your head down'.
If your being shot at down the street, thats something you cant really miss...unless your THAT oblivious to your surroundings.