On "polite snot rockets:"

The other day I was commuting home from work, taking the long route, which includes a 10 km stretch without a stop pretty much. I was passed by a "mature" (nearing 50, I think) roadie. Soon after passing me he made it clear that he was happy to have me drafting off his wheel, so I hung on. I noticed that he had to empty his nostrils a number of times, but he did it extremely politely, I don't know exactly how he did this but basically there was nothing flying in my direction, but he seemed to spare his bike, too. I was trying to crack his secret when he took a left turn (I was going straight) and said goodbye. What a gentleman.

Any clues?