Probably not. Was this the first time? Did you ask him about it? You should.
It's hard to say what, if anything, he has been doing with it, but if you know it hasn't been there before, ask him. Then if you don't believe him, you can stop sexual contact until he has it checked out. It may have been a temporary, light abrasion, or if it was the first time, perhaps it is natural for him.
Was there no discoloration or discharge?