Is PDA against any school rules? And can hugging my boyfriend even be considered PDA?

My principal yelled at my boyfriend and me a few weeks ago about kissing in the halls so we stopped but we still hug each other. Today I got yelled at for hugging him! Is hugging really against school rules!? And if so, shouldn't more people be getting in trouble? People hug in the halls at my school all the time. He only seems to have a problem with couples. Could this be considered discrimination?