DS is 18 months old and goes to nursery. He had a little bump at the weekend (nothing major, just a little bump just above his eyebrow and a small mark). We had to fill in an existing injury form when he went to nursery as we've done a couple of times when he's had the odd scratch/bruise.
Anyway, when they asked how it had happened, I that I was taking a shower and his brother (12, 13 in a month, he's my step son not that it matters) was watching him for 10 mins and he'd fallen when they were playing. She replied almost aghast that his brother had watched him and said it was "far too young to be responsible for a baby!!" 
He's nearly 13 and is very mature and absolutely brilliant with his brother. DS is a normal wobbly toddler so does have falls and scrapes every now and then and it was nothing his brother did wrong. I was upstairs for 10 mins and in the same house! His brother gave him a cuddle and he was fine, I didn't even know it had happened until I came down as he wasn't upset for long.
AIBU to be annoyed by the comment and think it was OTT?