Puppy constantly licking older dogs mouth

I have a 16w old puppy and a 12yo dog. My puppy is CONSTANTLY licking my older dog’s mouth. Inside his mouth, his cheeks, lips. All of it. She cannot be near my older dog without licking his mouth.

Is this normal? My older dog doesn’t correct her much, takes a lot for him to correct the pup. I do correct her myself and if she doesn’t stop she goes in her playpen to separate them. But I’m not sure if I’m handling that correctly, as I’m not sure if it’s normal or excessive.