Look around the glass for clear to yellowish mucus. The only time I have ever heard of a snake holding it's head up constantly is when they have an RI. Mucus and popping noises is the best way to find out if your snake has an RI.

Otherwise, I have a 5 year old female who has, over the years, become more bolder to the point she will stay out of her hides for days, especially after a good feed. The head raising is what concerns me about your snake. If it is constant like that, I would be keeping a close eye on him and watch (and listen) for other signs of sickness.

If you have other snakes or reptiles, be sure to remove him from the room for the time being, until you know for sure nothing is wrong with him.