I learned while doing some research that sperm can live in a warm place even in the open air. While yours wasn't exactly in the open it was still in a place where it could thrive. My guess is you're younger than most of us, be careful. Scientist have prooven that sperm can live up to 3 hours on a warm hand, and up to 7 days inside the womans body. Alway take care where u leave your 'gentalmen' and never take risk that even 'might, trasnferr. Protect yourself till you're sure your ready to take that leap into parenthood!
Good luck
I suppose it is plausible that there may have been the tiniest bit of semen left in her mouth that transferred to yours and then to your fingers. But honestly, I hiiiiighly doubt it. Sperm doesn't live long in the open air, so in the time you had your fingers out in the air if anything was on them it probably died.
Basically, I wouldn't worry about it unless she misses her period or thinks she's pregnant, in that case, get a test and find out for sure. Otherwise, don't stress, that sounds extremely unlikely.
Sometimes I feel like a very dark and sordid person, because the innocence in some of these posts is amazing. And it's not because I'm old :)