You know you have PTSD when, although you know that the faucet will sputter because of plumbing stuff having been done, and you turn on the faucet expecting the sputter, you still jump at the first sputter, and every sound after that feels like touching a sore spot.
... when you're in a morbid mood and enjoy yourself by making sudden loud noises to make yourself wince.
Or more generally speaking, when you're [DLMURL="http://www.youtube.com/watch?v=kdmd5fenroU"]this cat[/DLMURL] exactly.