A bunch of our pull request have been declined without anyone on the team doing that.
The activity view for those pull requests doesn't show a record for anyone having declined the issue. Other issues that were previously declined do show a declined record.
This seems to have started 2 days ago (2014-05-28). I haven't figured out what might be triggering it.
This should take you right to the evidence: https://bitbucket.org/coursepark/coursepark/pull-requests?displaystatus=declined