Re: kissing your baby on the lips
I used to peck my nieces and nephews on the lips - harmless as far I was concerned when they were younger. But once they turned two-ish we stopped.
With the youngest niece, when she would meet other kids she would want to kiss them on the lips. So then we instituted a “no lippy kiss” rule so now she’s not allowed to kiss anyone on the lips and makes sure to turn her face so you can only kiss her cheek, forehead, nose, chin - anything but her lips 