AITA for criticizing my sister's parenting?

AITA For telling my sister that her son shouldn’t ignore our grandmother? 28Y M.

Last weekend I was at my grandmothers place, and my sister's 4y old was there

too. He was watching his Ipad the whole time and when my Grandmother asked

him something he didn't respond or not even look up. It happened 4 times and the 5th time

I gently told my sister that he should not do that and he should learn how to respect someone

by listening and that being on the iPad constantly might not be the best for him.

She immediately got upset and told me that I don't have kids, so i shouldn't tell

her how to raise hers. I didn't mean to offend her, and i felt bad for