Important Question

I'm 12 weeks, 5 days & last night I woke up to use the restroom. When I wiped, I noticed there was some brownish/pink blood. Very little, but I don't know why I'd be bleeding. It wasn't caused by intercourse or anything like that. This morning I still wiped up very little, and it hasn't been enough to even show up on my underwear, but needless to say, I am freaking out & waiting for the OB to open. Has this happened to anyone?