Seat pitch on BAW A319

[BRUpax]

Did a couple of flights on BA's new A319 in Y class recently. On the first flight I was in row 15. I noted that the seat pitch was comfortable. On the return I was assigned row 17. When I sat down I immediatedly noticed a tighter seat pitch. As the flight was very light I moved forward to row 15 and yes it was definitely better by a good two inches. A further check after arrival confirmed that all rows 1 thru 15 had a greater seat pitch than row 16 upwards. Why is this? (C class was the first nine rows).

[OO-AOG]

I would guess that C class could be quickly extended to row 15 if required.