Who picks the tab?

Heyo!
Just back from lunch with S.. Had a good time. We went and saw a Lazyboy and will probably pick one up in the next few days.. We had our lunch at this place called 'The Village' and when it came to picking the tab I offered. My reason was simple: S just got a salary increment latter yesterday. He got a good raise because he worked hard. If I ask him to pick the tab- am I saying because you did good and are gonna get more mone, start by spending some on me? My view is, he has worked hard(ly) for it and deserves it. I should treat him to give a pat on the back (figuratively only)so he feels good about the letter (not that he wud have felt bad about picking the tab anyways). So if its one's birthday or anniversary, they should be treated and not the other way round (also that most people end up planning the whole thing to death and hardly enjoy the special day).

But thats the way it is. I paid and its different!! What say!?!?