I think my friend is in love with her brother...

One of my best friends at college is a commuter student, and she lives at home with her family. She has a boyfriend, they've been together for 5 years. But when I first met her and added her on Snapchat, I thought the man in all her snaps was her boyfriend..... it's her brother. I get sibling closeness, but this is.... a lot of closeness..... she snaps me every nigh a picture or a video of them and they're so close it looks like they're cuddling. I really think something is going on..... do I do something? Nothing? This is really out of left field I know, but I've had these thoughts in my head for months and I just wanted to share.... I don't judge her and never would, and I've never met her brother in person so I really don't have a good grasp on their relationship, but it really weirds me out....