Wait...how come girls are allowed to get away with this?

ok...so a few days ago, i went camping with a group of friends. when it was time to tent up, me and one of my best friends decided to share a little tent. (i've known this girl i was sharing a tent with for 2-3 years and we're pretty close. However, we have never done stuff etc. and there is not much ual attraction, but i still find her to be pretty) however, at night, i woke up to this girl reaching into my boxers and stroking me. we ended up having that night, and it was absolutely amazing. how much further should we take this thing? what overtook her to start doing this? help!