Picking finger?

Our five year old put his hand down in an ant pile accidentally today and got bit on his finger. I got out some itch cream and put it on the bite and told him to make sure he doesn't put his finger in his mouth now because it has medicine on it. He told me, "Don't worry Mommy, it's not my picking finger." I said, "What?" He replied, "Don't worry Mommy, I don't pick my nose with this finger, I use my other hand. I won't put it in my nose either. Don't worry." I'm worried.