My guinea pig licks my face, what does that mean?

  When I hold him close to my face he try to lick me, and I don't know why, and I am the only person he does it to.
This is how he is showing you that you are his companion and he loves you, isn't it great!! It also means you are doing a bang up job guinea pig parenting or he would not be relaxed enough to fall in love with you!! Congratulations and keep up the good work, Enjoy your guinea pig .
lots of piggys do that ..... for either 2 reasons.

1. You ate something and some of it is still on your face and they are trying to lick it off/eat it

2. They love you very much and are just showing there apreciation toward you

dont worry pretty much all piggys do this:)
He likes you, so he licks you!

Guinea pigs will often nuzzle and lick each others' ears, so he is doing the same sort of thing to you - he regards you as an honorary guinea pig!
He obviously loves you XD

Maybe your his favourite or maybe he just thinks you taste yummy:)
A lot of guinea pigs do this just to show affection.:)