I Had A Weird Experience

So recently I received a random FB request from someone I didn’t recognize. I didn’t have the time to investigate at time of the initial request, so several days passed before I could actually take a look at the profile and see who this person was and if we really knew one another.
So, while looking it appeared we had numerous mutual friends in common. All people I graduated HS with. So I just assumed it was somebody I just simply didn’t remember. Trusting that, I accepted the request.
The next morning I received a PM from this person saying HI. To which I politely replied in kind. Turns out it was my chemistry/physics teacher. We engaged in small chit chat initially. However, what transpired from there was quite bizarre! The conversation quickly turned toward an infatuation, and full of awkward compliments about my appearance.
2 days later ANOTHER friend request from yet another teacher, this one I remembered.
Wtf, is this not weird?!?!