I was recently at a shiur. The Rav printed handouts (pages of a sefer, printed from otzar hachachma). During the shiur, I was absentmindedly touching the papers with a finger that had a cut and saw that there were a few pink/red lines that got on the paper (I guess the cut bled somewhat and got on the paper). It wasn’t on the letters but I want to know if I have to apologize or ask mechila for that. I’d be very embarrassed to say something but I want to know if that is the halacha and the right thing to do.
You don’t have to ask the Rov mechila, because we can assume that he is mochel it. Unless the papers are used in a permanent basis, they will be 0put into shaimos after the shiur, and he doesn’t care about what happened.