lol. I get wet spots in my underwear all the time and I smell it to make sure and it will be pee. It's weird how it can come out and you don't even know it.
I did that around 17 weeks like 3 times in one day! I was so freaked out and called the midwife she sent me to the er and everything checked out good come to find out my baby was sitting on my bladder and I was peeing myself lol. But you never know if I was you I'd get checked out.
Did you smell it? Amniotic fluid smells sweet.
Id call your doc asap just to check you. Good luck.