I hope I'm not repeating info here, I did a quick search on this but didn't find anything.
Issue: rear taillights melting in their sockets
You Need To: inspect your taillights (brake / turn) for signs of excessive heat
Comments: I discovered both of my rear brake light bulbs melted in their sockets. The sockets themselves are burnt black and the drivers side tail light case has been hot enough to melt. A quick search on the Internet turns up a lot more chatter about this same issue. Even scarier is the fact that this happening with zero warning. No blown fuse, no codes, nothing to indicate your frying stuff in the back at all.
The dealership denies hearing anything , Ford denies hearing anything, even though it's happening all over the country and I found at least five other complaints listed with the National Highway Traffic Safety Administratiion.
What Can You Do: First and foremost check your taillights!! If they are burnt, hmm I don't have great advice as no one will admit its an issue yet. I happen to own a 2008 Focus which I've highly modified to include aftermarket taillights. I used the sockets from my original Focus taillights to replace the ones on the Edge. Now I'll keep an eye on them for any further signs of trouble.
Second, if you do find what I'm talking about FILE A REPORT. No one will do anything until enough complaints are received. It only takes 5 minutes and can be done on-line at https://www-odi.nhtsa.dot.gov/ivoq/.