Thanks for all the concern and advice! I drank a bunch of water, and the heating pad helped a whole lot. I wasn't sure if they were legit contractions, because it was only lower... and the tightness felt more like muscle tightness (nothing like BH, which I do get a lot of when I move around too much). It also didn't feel like it was coming and going, more like a constant tightness. I dunno. If it happens again, I'll definitely call my OB. I think I'm "all better" for now, though!
Thanks again, y'all :)
Also, to PP who asked, I'm 27 weeks. Definitely not a good time to have contractions, if that's what was going on :|