dumerils boa acting lethargic

[breakofsanity]

I have a 6ft dumerils boa that is acting lethargic. I got home from work almost 4hrs ago and he has been laying in the same position ever since i walked in the door. I just figured he was sleeping until just now when i was misting him. Usually he will start moving around a little bit while i mist him but this time he just kept laying there. When i misted his head he moved it a little bit and flicked his tongue, but he didnt move his head much at all and his body didnt move. I am still sort of a novice snake owner so any thoughts on what could be wrong would be very helpful. Thank you.