I'm pretty sure that's Jon Gries who played the hunter, Martin Creaser who'd committed himself to the mental hospital in 5.11 "Sam Interrupted". I really hope they're bringing that character back, I really liked him a lot. Especially if this is a flashback that shows Sam was actually hunting/doing something to find Dean and Kevin during his year without Dean. Because hey, why not? Martin could have been a resource that Sam could have called on...especially if he'd gotten scared straight back into mental health by the wraith hunting in the hospital with Sam and Dean.
Or maybe it's another wraith case that Sam and Dean have to deal with, which I'd love, because I thought the wraith was a really cool foe, making them go crazy and manipulating them with their own greatest fears.
I know it's no big deal to notice this, but I love it when they either re-use actors or bring small characters back on the show.
Anyways, he looks good, and healthy compared to how he looked in 5.11, so I hope he's still a hunter in some way, shape or form.
Oh and Sam, whatever you're doing with your hair, keep doing it you look fabulous darling.