We were proud that no software defects showed up during the acceptance tests.
Not all of the acceptance tests have to pass all the time.
For an agile team, it should also mean that all the acceptance tests pass.
In fact, on a less Agile project that is contract-driven, the customer often specifies the acceptance tests as part of the contract or as an addendum to it.
When all the acceptance tests pass for a given user story, that story is considered complete.