I have to agree it's normal and they're showing each other affection. My babies clean my hubby all about his face when he get's home. They're are some dogs that nervously lick I had a dog do that to his feet but I just let him he wasn't hurting anything. And exotic birds will pluck they're feathers out form nervousness but it doesn't sound to me like this is whats happening. You should just let them be and try not be annoyed by it
You probably do things they get annoyed by too and they forgive you 