I agree... little dogs also love to preen their owners.
Everytime my husband walks through the door, our small 10# dog starts preening his feet as soon as he sits down. The dog does not care if my husband is wearing shoes, just socks or bare feet. It goes on for about 10 minutes or more.
The dog nibbles with it’s small front teeth, as if it is cleaning and preening my husbands feet.
The nibbling that dogs do on their owners is a sign of love an affection. I think they think they are nibbling fleas.