I sent you a text with a pic, cf, but i see you found the other one.
Rebellion have history with mucking about like this. Im a constant reader of their Tombs of the Dead series, and the ten books so far have three very different spine designs, plus another change of coverstock (shiny to matt). The series went from normal sized paperbacks to oversized after book four, and has recently been revamped as of book ten ('the viking dead') to a shinier and completely different style.
Normally, i'd say changing stuff is good- it keeps browsers on their toes and reinforces the 'newness', but all the same, it's ever-so slightly annoying. To get my own back, i shelve that particular series backwards (10-1, not pages-out) so they merge gently with other similar paperbacks on dedicated zombie fiction shelf number two in the lounge.
I may go and kill myself now, having read back over that.
SBT