So I've been hosting at a restaurant on the weekends.  It's only been for a few months and started as a favor, but I do more than just host.  Hosting isn't very demanding so I have downtime, and during that time I like to help out by busing tables or helping the servers with what is supposed to be their job in a variety of ways.  Some days I help a lot more than others depending on how busy it is or my mood.  But really, i'm not expected to do anything but host.

In time, one server has tipped me out several times on those nights I was helping a lot.  The other servers have not (only 3 servers total) ever tipped me.  Part of me feels bad, because maybe they would rather me not help because they'd just want to do all of the work themselves without feeling guilty or obligated to tip me out.  So, should I just stop helping?  Would I be an asshole to only help the one server who tips me out while not really bothering to help the others who never have?