That is interesting. Could just be unique to him, as how he expresses affection. Does he lick other stuff? If he does spend time licking random stuff id have him checked out. If its just you he lick probably fine.
None of mine lick me, I just get kisses and preening
A crossover Quaker Scuti (F), A Sun conure named AC, A Cinnamon Green Cheek conure Kent, and 6 budgies, Scuti Jr. (f), yellow (m), clark Jr. (m), Dot (f), Zebra(f), Machine (m).