I just got a bunch of achievements that I'm sure I already have. Are they being reset or something?

Yes they are. The achievement system is being redone again and being fixed as people had them yet the system made it seem they did not. If you look now you will have them all (the ones you had beforehand)

OK, thank you.

Thanks , I came here to ask the same thing.

And congrats , your only 1 post away from 1k!