UPDATE:
today I found out that one of my co-workers bought our other coworker a tiny tabletop drum set. I thought, oh cool, and went about my day. About three hours later I had the thought, "wait, didn't he get one of those last year too?" And it suddenly really felt like he HAD, and i thought I had a memory of him getting one. This all was accompanied by major anxiety of me worrying that it never happened. So I went and asked him, and he hadn't.
Then i realized I may have been remembering my cousin a couple years back who did get the same thing for Christmas, and i think i knew someone else who had one at one time but i can't remember who.
This really bothered me and I still feel like I'm going crazy.