Nursery staff kissing my child

My son is at a local nursery and he loves it there. Today I saw something and it really unsettled me. I went to pick my son after work and I was watching him play outside whilst talking to a member of staff about his day. When I saw that another member called him over and kissed him on the lips. I have seen this staff member do this to other children (harmless an sure) however as a personal choice I just don’t agree with it. And it’s really annoying me. I will be speaking to the manager to ensure it doesn’t happen again however how does one approach this without offending anyone. What are people’s thoughts on this ? Is it acceptable to be kissing other people’s kids on the lips?

hmmm, not something I'd be all that comfortable with and I'm pretty happy go lucky with most things. I remember when my eldest started nursery I saw a member of staff kiss a baby on it's head. I remember thinking it was a little out of the ordinary but then realised as it was another staff members kid, they were probably closer. As my child was at the nursery longer and I got to know the staff more, I wouldn't have been alarmed if they had kissed him on the head or shown some affection.
But kissing on the lips is a no no for me. I know some parents who don't even kiss their own kids on the lips (I do, but I know some people aren't keen on it). It's also a big paranoia for me with babies and spreading the coldsore virus.

Best to raise it with the manager in a polite way.