BB,
Not a silly question at all - I saw the same on my pay statement and wondered the same. They have made so many changes with JPA that I thought they might have slipped this on in unannounced as well.
However, I had a read through the intranet online version of the new Pay JSP (753 if my memory doesn't fail me), and it was very specific that officers don't get AIPs only SNCO downward.
Perhaps JPA is a little ahead of the game for once
and it has been given AIPs so that the software doesn't need to be amended when the AFPRB/MOD finally agree to them.
If anyone knows any different I would be very interested as it would mean a reasonable pay rise
D4R