Actually it was A343 that was scheduled (same cabin size, 4 engines instead of 2) and those have been recently refitted into 2-class conf. You got lucky to have it changed last minute to a A333, that is a 3-class aircraft. Nice ^

This might occur even more often on the 2-class routes when all of the A343 and B744 will be stripped of F. So booking seats in rows 1 and 2 might be a good idea. Looking forward to that