I Gave My Boyfriend A Handjob And He Did Not

I gave my boyfriend a handjob and he did not cum or pre cum but is there a possibility there could have been semen/sperm under his foreskin from him masturbating in the morning? Can sperm be active under the foreskin and for how long? And also can sperm be alive under my nails if some did get there? I washed my hands after we did but not under my nails.