Danny, that does ease my mind slightly, thanks.
Update: I spent the better part of the day trying to duplicate the failure with a second identical incubator and temps.
I got the incubator stabilized up to 89.6 degrees (what I incubate at) and turned on the interior light to mimic the failure so that I can monitor the time it takes for the incubator to get to 98-99 degrees, and more importantly, the time it takes to get an egg (a nice big white unviable egg) to get to 98-99 degrees.
I can only assume that the less time the eggs have been hot, the better chance I have of them remaining viable.
After three full hours, the incubator has only risen 4 degrees and the egg only 1.5-2 degrees.
Here's hoping...