Found a disturbing skype chat?

Alright so I was using my brother's laptop... I needed it for school and none of our other computers are working. His skype account popped up out of nowhere and I read about 2 lines of the most atrocious vulgar chat I have ever read...honestly im not a little kid I've been creeped on, I've gone to highschool. But I was so disgusted...especially since it's my big brother's business it makes things even more awkward. I exed out immediately and have not brought it up to him since he's an adult and should be free to do what he wants. Problem is...he acts or pretends to be extremely orthodox and he is going to settle down soon with his on-off girlfriend. Should I bring this up to him privately or just drop the whole subject and forget it ever happened? Im kinda scarred lol and I know it his account and his chat. No one else uses his laptop ever.