is this weird?

Sid
I'm in this math class in college and there's this group of girls who seem to be really close to the professor. 
 On the first day of classes several other students including me went to sit in the front row and he stopped us and said those seats were saved. We all questioned it but we moved anyways and then this group of girls came in and sat down in the front row and started talking to him but like not in a completely flirty way but like they were giggly and smiley. 
A few weeks into class my friend and I noticed that one girl literally follows him from his first class to this math class. Like she's always with him. Another time in the hallways we saw them all following along with him walking in a group talking. 
Today in class, we had a quiz and I turned mine in right after one of the girls did and he was like waiting by the door because we could leave after, just hand it to him on the way out. Anyways the girl handed hers to him and as I was handing him mine he like, turned and gently grabbed her arm and stopped her and said "see ya later" then turned and grabbed mine.
I may be over thinking this but I find it hella freaking weird and I'm not the only one. She was also taking snap chats of him at the beginning of class. I get some professors are close to some students but there's a boundary.. I feel like this girls don't have one with this professor..