Ticking Sound - Evap Canister/Shut Valve?

Lately, I've noticed a ticking sound that appears to be coming from under the rear driver's side door. It isn't terribly loud, and I don't really notice it while moving. I can definitely hear it in idle though. However, it isn't constant. I noticed that when I started my car this morning to let it warm up before heading to work, I didn't hear the tick. I didn't think to check when I got to work, but I believe it was at that point.

I did some research, and it sounds like it could be the evap canister. I found this post:

http://acurazine.com/forums/second-g...cement-729920/

It really sounds like it's coming from the bottom of the back driver's side door itself. That is, until I would lean down and listen. Then the noise seems to be further away, as in less by the door and more toward the middle of the underside of the car.

Most likely evap canister? I don't have a CEL or anything, but I read in other places that it can still tick without a light. That it doesn't mean it's "all the way bad", but that that the evap canister losing its touch, so to speak.

Is there any particular way to know if it's the evap canister going out? Any sort of "test" I can do? Also, anyone have a diagram showing exactly where it's located? I'm pretty sure I saw it when I looked last night, but I want to be positive so I can hopefully isolate the ticking sound.