Do you ever experience an unexpected surge of joy?

This happens to me sometimes when I come out of the shower.

I experience it when I’m in my robe. I laugh quietly with my mouth closed, sort of similar to when you have your mouth closed, but are smiling with your teeth showing and exhaling from your mouth.

What does this mean? is it some sort of memory/reptilian function that makes me remember when I was a little boy and my mom was drying me with a towel and tickling me at the same time? or am I going crazy?