It sounds to me like your snake could be favoring the type of hide that you have on the cool side and is compromising its thermoregulatory needs for security.
If it were me I would get another hide like you have on the cool side and bump your temps up to the levels freaky_frog suggested. The herpstat should help with that. Also, to keep the overall ambient temp up you may try covering three sides of the tank with that pink foam insulation. I had success with that when I had glass enclosures.
Hope this helps.