It's "normal" in the sense that it does, as you mentioned, happen from time to time. Is there any good reason for an empty tanker to remain with a group, none that I can think of. Even if the way home is through perilous airspace, it would make more sense to detail a couple of fighters as an escort than to have it tag along.
The problem I see most often is when after a refueling is done and you approve the split, your RTB options do not include the carrier you launched from, but airfields hundreds of miles away.
Tanker ops have always seemed to be on the hinky side, so much so that I try to avoid using them at all.