Agree with others, the simple answer is it doesn't interest you. Finding out she has a predilection for something you find unacceptable has come as a shock after being friends for so long.

Life, with or without social media, will always deliver surprises or shocks. You have the choice whether to join in or not. How she accepts your comment will show how strong your friendship is.

Whilst reading posts on this site, I've received a message from a member of the website where I write a blog. To say I was shocked by what he'd written is an understatement, as my contact with this guy has only ever been on social media. Will be interested to see if moderator passes any comment. Some people feel the need to say something instead of keeping quiet!!