Do you hold a grudge after you first meet someone?

Tweet

I recently met this guy at school and he and I got into a coversation about our school. I made a little innocent joke and he snapped on me and make it his duty to educate me on the subject 100% in front of the whole class. I didn't really appreciate this and since then I try not to talk to him because of his behavior that one day. Am I being childish or do I have a right to still be upset?? My ex told me I never let stuff go, is this a good example of that?