Just go look at what Apple did to O2.
They did a secret deal with Vodafone so they could get the iPhone.
Vodafone could not go public with because Apple was in talks with O2 at the time and Apple let O2 assume that they were the only one they were in talking with. This got Apple a better deal with O2 but it only works once. After that companies will assume Apple always doing something like that behind there back and will treat apple as such.
The trust is gone.
If there was no exclusivity contract involved with the O2 deal then it is strictly ignorance on their part. Apple's deals with carriers are never done out in the open, so of course neither O2 nor Vodafone were out talking about it.
EDIT: Or, what OllyW said.