Is it normal to have an / without any contact?

I think the most embarssing thing in a very long time happened tome today, I was sitting in my living room with my girlfriend and our kids and I starting looking and my girl (wantin her real bad) and thinking about me and her having out of no where, my drive has been on overdrive and we haven't had in 4 months since before my son was born, all of a sudden after about 15 min my d*** starts jumpin and i feel my boxers get wet the only contact i had with anything was the floor i left the room and got cleaned up but I don't think they noticed what happened, is this normal, I have never had anything like this happen