Favoring citations in the same journal
It is not unheard of. For a journal that I submit regularly to the instructions for authors state


  Given that the Journal has been in existence for over 80 years and has
  published of the order of 35,000 papers on a wide variety of
  acoustical topics over its lifetime, the absence of any references to
  previously published papers in the Journal raises a flag signaling the
  possibility that the paper lies outside the de facto scope of the
  Journal


I think it really is a scope question and not a self citation question. That said, the handling editors of this journal often alert authors during the later stages of review of potentially relevant in press publications within the journal. Most have been relevant and I am happy to add the sentence or two to the background, but I also think of it as a clear attempt at increasing self citation counts.