Kissing on a new baby !!

So basically last weekend I went to pick up my 3 month old from my boyfriends aunt after work and she was kissing all in her face .. I really hate the thought of somebody putting their lips on my baby because of germs, infections, etc. Would I be wrong to tell him to talk to her about not doing that anymore , because she's babysitting tomorrow and I can't stand to think about her doing that again.