Eeriness
Something on my system is periodically relaunching Terminal.app.
This is almost certainly my own fault, but I can't figure out what I did. Part of the problem is that I have no idea for how long this has been going on; I normally have the terminal open all the time, so this effect wasn't making any difference. The other part of the problem is that I have no leads on tracking down the culprit, since whatever it is, it likely only runs for a fraction of a second while doing its inexplicable work.