Given that they can only use the A320, and not the A321, on the GIB route that is my thinking for why it is always quite late in the process that the flights to GIB get finalised.
It has been the same at every single season change I can remember. And given the current limited competition, they can be quite flexible with the plans to enable them to maximise their return from the frame in other areas.
[They are after all the airline which has the best timed flight departure exGIB and have been for some time (post 5pm Friday departure).]
Fed up with all the rumour mongers trying to read stuff into it, this has been the case every season change. The key indicator is how many services they offer and how that varies over the period. They are not going to drop the routes.