Are you saying you don't like it when something goes soft before it was supposed to?
I am not familiar with these Cooper's bottles. It sounds different from what I am used to seeing . . . unless they are the same type caps as you would find on two liter bottles of soda? If that is the case and the bottom ring is separated than it sounds like maybe the pressure in the bottles popped the seal just enough to release the pressure and, alas, go soft prematurely. With no consideration towards you at all. The cads.
On Tap: 1. Kelly R. IPA, 2. Roter Hund Hefeweizen, 3. Bud Killer Blonde, 4. Red Dog Pale, 5. Roter Hund Oktoberfest, 6. Pumpkin Ale, 7. McRed's Stout (with new nitro system and stout tap,) Cream Soda, 8. ESB # 3, & 9. Ordinary Bitter.