cheeses, particularly French and English regional cheeses, are often seasonally produced. The bigger brands are usually available all year round, but you may find that some come and go as the seasons turn.
This is part of life's rich tapestry.

Yes, I know some cheeses are seasonal. That's why I waited well over a year before ranting about Sage Derby, to deal with the possibility that it might just have been out of season :-) And precisely because St Paulin is very similar to the two other cheeses next to it, it seems unlikely that it's gone out of season while the other two haven't...