Lol @ pig. I'd say he's perfectly happy and things are going fine. If he's not playing with the bit and he's grazing fine with it, then I'd say he's just slobbering happily along.
Dumas would slobber with a rabies-like amount when given apple slices, it was nasty and gross but he loved every minute of it. The only problem I had with the excess slobbering is that he used his white (light grey) buddy as a napkin.