If your therapist has sent a friend request on purpose that is definitely inappropriate, but I'd talk to them about it first because there could be a perfectly innocent explanation. My Psychiatrist, his wife, and his brother constantly come up as friend suggestions on my Facebook profile, simply because we all have other Facebook friends in common. I'm sure it works both ways and he's probably gotten a friend suggestion for me. What if the same thing happened with your therapist and he clicked on the suggestion wondering why your name was coming up like that, and accidentally sent you a friend request instead. I don't use Facebook on mobile, but I suppose something like that might happen with different platform, or if, like someone else mentioned, Facebook was being a bit bug-y.