It wasn't bluesy at all. It had a very slow, methodical muted guitar. Hard to describe. I should have asked the guys at the soundboard back on June 14th, 2003!! I wouldn't be racking my brain to come up with the answer!
A comparable band is "Explosions in the Sky", who worked on the Friday Night Lights soundtrack. They are close, but it's definitely not them.
Thanks for the welcome!