Bowing to the priest at Mass?

I happened to attend Mass at a chapel across town the other day and noticed something I'd never seen before. When each lay reader approached the ambo, he bowed...to the seated priest. What's up with that?

Normally I see lay readers reverence the altar by a profound bow...but not the priest. Of course, prior to proclaiming the Gospel a deacon will bow to the priest and ask for his blessing. But a lay reader? Anybody familiar with this practice?