My three year old son goes to a childminder with another three year old boy. The childminder asks for a bag of spare clothes which we provided including a spare sun hat. They went out on Friday to the park in the sunshine and the other little boy had forgot his hat and didn't have a spare. So childminder used my son's spare sun hat for the other boy. She didn't ask my permission but I didn't mind as I'd hate a little one to get sunstroke. However, at the park the other boy lost our spare sun hat. I've just received a message from childminder asking us to provide a replacement spare sun hat for our son. AIBU to think that the other boy's parents or she should replace the lost sun hat? I don't have another spare so it'd mean me purchasing one.