Why the cold side?

My corn is about 4 months old now.. She has a rock on the warm side and a water dish on the cool side. Lately all she does is go under the water dish which isn't small it's pretty heavy she goes under there and moves the bedding and lays right on the glass and she's cool to the touch. She has always gone under there but not usually for very long her skin is discolored and has been for about a week. I haven't seen her come out in a week she has been under the water dish. She seems healthy when I hold her and she ate two pinkies last night so apparently she's okay but why the hiding under there all the sudden? After she ate last night she went to the warm side obviously to digest. I know she's about to shed does this have anything to do with it?

Just the rock and the water dish? What are her other hides?
Snakes are cool to the touch anyway, our tempatures are higher than their's so even if they are warmer they still feel cool to the touch unless they've been sitting right over the heat. But the waterdish provides a secure pressure and she obviously likes it.
If you want to give your snake more chances to be "out" you should really give her more hides. A rock to sit on top of doesn't really count as a hide.

Yep, Jenn is right, there should be a minimum of 2 secure hides. One on the cool side and one on the warm side. If she's about to shed then she will be appear discoloured, that's not a result of staying under the water dish for too long.

I would like to elaborate a bit if I may,

During a shedding cycle and pretty much most of the time- the snake will prefer spending time on the cold side. Their metabolism quickens when their body temperature rises, and so the "hotter" they are, the more quickly they digest, the more oxygen they need and their heart rate accelerates accordingly.

When they get colder, they burn less calories and need less food to sustain themselves. Mostly after feeding they will go to the warm spots, so that their body can digest the food efficiently without it getting rotten in their stomach(which can lead to regurgitation and can even prove fatal)

On the matter of being in shed, I think they prefer being on the cooler side for two prominent reasons, one of which is due to the other:

1- They feel vulnerable, indeed much energy is required to complete a shed cycle. They are also partially blind at this time. The cooler sides are often darker and there are hides in which they simply feel more secure in.

2- Since they hesitate to travel in this time, they need to conserve their energies- a state which they can accomplish by staying cold.

I probably stated the obvious in this by I wasn't sure because there was little reference to the title of the thread itself.

Hope this helped, somehow.

She is colder than usuall I should say. But she has two hides one on one side and the one on the other. She is definatley going to shed soon. Thanks for your help hope pics help too...

After I moved the water bowl this is where she stays

Yeah she's hiding under the water dish because it's secure and snug.
The other hide is great for when they're older, but for now it's honestly not doing her any good.
For hatchlings hides that they can feel up against them when they're curled up are recommend (hence her hiding under the dish). It may not look pretty but toliet paper tubes and sandwhich boxes work great, I suggest putting one on each side.
Hope this helps