Henry does this to my OH but no one else - mostly. Henry doesn't see much of my OH during the week and on Saturday mornings OH gets up before me and spends time with Henry. If he sits on the sofa Henry will jump up and give him a very thorough licking, with a few nose nibbles thrown in.
Today I had to take Henry to the vet to have a sore ear investigated. He was as good as gold when the vet was in the room. On the two occasions she left the room, he immediately started frantically licking my face and nibbling my nose.
So it seems to me it is some sort of expression of... something. Appeasement maybe, to OH to say: 'Where have you BEEN all week, do you still love me?' And at the vet today - maybe a release of stress and tension when he found himself in a safe environment with just him and me?