Manager expects me to cover for travel childcare

Okay so this is semi-rant, semi-question. I have a work trip next month (pre-planned). My manager just asked if I could "take one of the team members' kids to school" while they're on their own trip at the same time.

Like... no? I'm traveling for work. I have my own kids I'm figuring out coverage for. Why is this my responsibility?

Am I being unreasonable? It felt really presumptuous.