mom caught me...

so my mom caught me masturbating and she wasn't mad but she told me she has caught me a few times and that i need to quit messing with myself. why is she saying this?

edit: i know some of you guys are trying to make this my fault for her walking in on me, but my door was locked and she unlocked it, and i was under a blanket. not being rude to anyone but if you don't have anything nice to say, don't say anything at all :). please be more understanding.