ExH and are share 50/50 care of 4 yo DS. Last week he had to go away for work on his days (which is very rare) and unfortunately I couldn’t have DS as I was also away for work (as I often am when I don’t have DS) ex said he’d arrange for DS to stay with his mum who lives nearby and who DS is very close to & comfortable with and who he’s stayed with many times before. I said that that was fine. However this week I find out that his mum couldn’t have him and instead he stayed with ex’s friends- DS knows them quite well, they’re a couple, no kids, have a nice flat & had a spare bedroom for DS. However he’s never stayed with them before. They’ve babysat for him before but AIBU to think it was completely inappropriate for him to stay with them in an unfamiliar house for FOUR days and 3 nights?! He’s only 4, I worry that he must’ve been really uncomfortable there and I’m pissed off at my ex for doing it. But maybe I’m being unreasonable about it?