I need y’all opinions on this

Having a “girl” moment right now.....not sure if I’m overreacting—backstory, my current 5+months boyfriend was absolutely heartbroken over his ex (who he was engaged to). They bought a cat together and when she left him, she took the cat with her. Granted, he still had the other cat but of course he was torn up about it. Said he wasn’t in contact with her, etc etc. today he randomly texts me super excited he gets to babysit the cat that she took from him...now, I my head I’m wondering 1. Was she so desperate she resorted to asking him cause no one else could do it 2. She’s trying to come back into the picture 3. It’s completely innocent and she just wants him to be able to see the cat. It’s not that I’m ultimately upset, but I asked him casually how that came about and he got super defensive—which isn’t a healthy way to respond to a simple (valid) question. Would you be as annoyed as I am?