Chain of commandwise, I suppose Worf would have been the Third Officer by this point anyways, so it really wasn't a huge jump.
Worf's rank was always weird, throughout all the shows. He was a Lt. for far too long in TNG, as a department head he should have been a 2-and-a-half. Even one-episode department heads usually held this rank. Of course this is again throughout Trek, step forward Harry Kim...
Worf in his later career, where Kira had essentially reached the rank of Captain in the Bajoran militia, should probably have gotten three full pips, but he did piss off Starfleet by getting their spy killed.