I had this happen once, but when I tried to replicate it in a dev environment to try to trouble shoot it, I could not force it to repeat.
I was in HSHA, mirroring is supposed to prevent split brain issues like this from happening, but that is exactally what I did, recovered one set of databases and re-initialized mirroring.
What is the build version of your 2008 server, sp1, sp2, sp1 & some CU's. There was an issue with the way the transactions were passed along in mirroring that could cause mirroring to enter a suspended state, that was fixed in CU 5 for sp1 that we applied, but this is completely seperate from the issue you are posting about.
If your running SP 2 it would have been fixed in there as well.