TMI warning !! Would you be alarmed? Update

My brother took my son out To eat and play today. He mentioned wiping my sons but and I was like oh he pooped? My brother said no. So I asked why’d you wipe his butt? And he said to make sure there wasn’t anything left over in it.

I just found that weird and it made me uneasy. Maybe because my Bestfriends son was molested by her brother. I tried talking to my 4 year old about good and bad touch but he doesn’t understand

Edit: my son is 4 and not in diapers. He just needs help wiping when he poops however he didn’t poop. He peed. My brother claims he wiped anyways to make sure “nothing was there” but idk why he’d do that if he knew me son only peed