Who knows Andrew ? - if the categorisation was being done at squadron level then there could be a variety of reasons.Perhaps the original assessor had a rethink and changed the cat retrospectively or perhaps the pilot concerned screwed up on a sortie (but not too dangerously) or even perhaps the assessor had simply put the wrong cat down by mistake.
Would OC 201 actually be doing all the recat flights ? - there could have been a little misunderstanding between OC 201 and the actual checking pilot (if not the CO personally) and subsequently rectified in log book.