Issue with a new diamond dove

[cye]

Hoping I can pick some brains here.  Not new to birds, but I am new to doves.   I came across two diamond doves today at a pet store that had been a special order that had never been picked up.  I've always thought diamonds were pretty, so I talked with a knowledgable associate there for quite a while about them until I was sure I'd be able to care for them.  One thing I noted, and he did point out was the one kept tending to hold it's head on it's back.  He said both birds had just been taken to the vet about it, and that it seemed to be stress related.
Has anyone else seen this in diamond doves?

[allien02]