Did you wash it after it's returned? As you said, you would, right? I guess you even used hot water. If so, you don't need to worry, risk is extremely low unless the God hates you. If you didn't, two mistakes you have made: 1.You should not lend it out, 2. You should clean it completely after it's returned.
Lots of people, like this angry mom, scare something with no knowledge. and the worse thing is, they also scare to know the correct knowledge. that's sad because they treat others unfair while losing their peace life