Being "Defriended", do you ever retaliate?

[Burdzthewurd]

Just noticed that an ok friend of mine (we'd talk once-twice a week, she was really open about everything and friendly) just blocked/defriended me on Myspace, Facebook, and an online journal site for no particular reason. No argument or fight with her, as the last time I spoke with her was about her recent ex-boyfriend who screwed her over and conveniently was also an enemy of mine. I'm not gonna go messaging death threats to her or sticking a banana in her tailpipe, but I am mildly annoyed. Does everyone else just shrug it off and move on, or have any of you done something irrational or at least humorously mean-spirited in revenge?