I don't think it was your bands unless I misunderstood your message. If it lifted in the front (most likely) then the loop would have tightened. If it lifted in the back (hard to do from what I understand) then the loop would have lessened pushing the tail down or back.

Anyway, good rule of thumb I have been told by several people is:

After 3 or 4 flights, replace your bands if you are pulling speed ...doing loops or placing any type of stress like this on the wing.
NEVER reuse rubberbands..Ever!

Good luck. This message has prompted me to make sure my bands are fuelproof. I replace after 3 flights mostly because after my 3rd flight one day I was doing a preflight inspection. NOticed one motor screw almost completely out. And also noticed one rubberband off the dowels dangling because it snapped. Makes ya think.

S