Well, I would've sworn to you it wasn't recording when I was muting the mike volume. But just now I muted, and it still recorded. So, yay.
Interestingly, sound recorder, at one point, recorded audio from a movie that was playing in the background on my computer, even though my speakers were turned off. So maybe the thing mysteriously set itself to record only noises coming from the computer, or something? MMm.
Thanks for the help.