That's an interesting possibility. I don't have any particularly strong memories of being warned about choking hazards, about the only one I remember is warnings about plastic bags.

For lentils, I'm fine handling them in bulk, and eating spoonfuls of them doesn't bother me. When most of them are gone, and there are only a few scattered in my plate or bowl they start to trigger the revulsion a little bit, although not nearly as strong as many other things.

This actually seems to suggest that there is some desensitization going on. I never had lentils until I was an adult, I have however been eating rice for as long as I can remember, and individual rice grains don't trigger the reaction under most circumstances. Small candies, like skittles, m&ms, smarties, etc. don't really trigger it either, in most circumstances, which again, I have been eating since childhood.