Feeling uneasy about seeing my FWB shortly after her date — is this normal?

I’ve been friends with benefits with a good friend for about two months now. She goes on dates occasionally, and this Thursday she has a date near where I live. I don’t know, it just feels a bit off—and honestly a little gross—to be meeting up and hooking up with her literally an hour after she’s been out with someone else.

What do you all think? Am I overthinking this?