2006 MC1500
I haven't investigated this yet, but I thought I'd throw it out there in case any of you have had a similar experience.
I don't know how often it happens, but once in a while when I get out of my truck, I notice the brake lights are on. Just a little lift on the pedal and they go out. Any ideas?

 

Look behind the pedal, there's a switch / sensor that controls the brake lights. Happened to me a while back. Easy inexpensive fix.