My teacher kissed me?!?!?

so the school was doing a camp thingy like a trick every year in the summer and there was a dance and i had a random mood swing and went out side to relax and my teacher was worried so he came out to check on me i said i was alright and then we kissed for like a minute or something then he stood up and has a face that was like WTF?!?! aka shocked at what had just happened and he excused himself and went back inside can some one explain what happened i'm confused (btw there is a 4 year difference from me and my teachers age)