Please give me suggestions!

My daughter is seven now. I just got aware of that a boy in her class hugs her and kisses her on her cheeks every day. He does that in one of the cubicles in the classroom used for kids hanging on their back packs, jackets, and etc. (The cubicles have no doors and each one is shared by two or three kids) He once even tried to kiss my daughter on her lips but gave up as there were some kids already watching them. My girl lets him hug and kiss her because, she said, that was so sweet.

My daughter did tell me several times, during casual chatting between me and her, that some boys often go to her desk and talk to her between classes, that those boys always keep watching her, that a boy (not the one mentioned above) even said: "I have a crush on (my daughter's name)", and that a girl asked my daughter if another boy in her class has a crush on my daughter. I also noticed that only my daughter and another girl were invited to those boys' birthday parties. I did not take it seriously as I thought those were just friendships between the kids. But this time I feel that I can no more wait and see - I am pretty sure I would have stepped in and stopped it if we had been in china.

Considering the culture here, I am not sure if I am wrong or not. Do I overreact? If not, what I need to do? Or I just still wait and see? I don't think I am a conservative person, but for the sake of my daughter that is only seven...

Your opinions and suggestions are greatly appreciated!

Thanks in advance!

Busy and worried mom