Looking after next door neighbour's cat while she's away. Yesterday, I gave the cat a fuss as usual. She's very affectionate and sits on my knee for a cuddle. She jumped down after a while and, when I went to pick up the empty food bowl, she bit my arm. Didn't puncture the skin but it's left a mark. I wasn't touching her so can't have touched a sore spot or anything like that. All I can assume is that she was really hungry and thought I was taking food away, rather than giving it.
My question is, do I tell the neighbour? She lives on her own so no children, etc, at risk of being bitten, but do I warn her? She'd be very upset and I don't want that. Her cat is her only companion.