Am I overreacting?

So the other day my SIL came over with her kids for a play date with my daughter.

I just finished decorating the nursery and showed her the finished design when she came over.

We were playing outside and she went to put her youngest down for a nap. About an hour later she went to go get him and casually said oh I hope it’s okay, he’s sleeping in the baby’s crib. I didn’t say anything bc I was kinda shocked she didnt ask first. I didn’t say anything at the time but as time goes on I’m just sorta upset she did that.

I wanted my little one to be the first to sleep in her room and I’m just frustrated she assumed it was okay.

I know saying something won’t change anything but my feelings are genuinely hurt.

Am I overreacting?