Teenager doesn't care about privacy in regards to nudity at home. Is this a sign of abuse?

We never made a big deal about nudity in our house. We didn't run around naked but I showered with both of my boys until they were school aged and they bathed together for even longer. My oldest got more private around puberty. I figured that would happen with the younger one as well but it hasn't. Again he isn't walking around nude but he'll often leave the door open while getting dressed or using the bathroom. He'll adjust a towel in front of us or will jump into the shower while someone is in the restroom. It doesn't bother me much but my mom thinks it is a sign that he is being sexually abused. I think he would tell me if something was happening and he shows no other signs. He's a happy and normal teenager. I asked him about it and he was confused and said nothing is happening. Should I pursue further or drop it? via /r/Parenting https://ift.tt/2pOJXrO