Tarantula Molting & Soil

This past Thurs. evening, I gave 1 of the crickets to my Chilean Rose & he backed away from it after I placed it right in front of him & he didn't grab onto it at all like he normally does. For the rest of the night, my Tarantula just sat off to the side or in a different spot & didn't seem interested at all in eating the cricket, so I removed it out of there the following morning. I'm beginning to really wonder if my Tarantula's possibly getting ready to molt? I know I read around Feb into March is when Tarantulas molt. And when they're getting to molt, they lose interest in all food, are less active, although my T still crawls around, but not a lot recently & their color darkens too. Or possibly my Tarantula just wasn't hungry? I did read & heard too that tarantulas can go months w/out eating, or even weeks for example & not to worry. Should I go ahead & offer a cricket to my Tarantula tonight to see if he'll eat it right away, or should I just wait a few more days or a week even to see if he's really getting ready to molt? I just don't want to throw a cricket in there & for him to get all stressed out & all. I also haven't been holding him like I normally do once a day for the past 2 or so days since I don't want to stress him out if he's getting ready to molt. I know that when a Tarantula's in the molting process, they'll be lying on their backs w/ their legs in the air & other people sometimes think that they're dead!

And I also threw in 2 1/3 cups of the eco earth substrate 3 days ago & mixed it in really good w/ the rest of the other soil in there, esp. making sure to mix it up well on the bottom where it seems to still be damp. The humidity went up to 67% after a while, then to 64%, 60% for example & later at night, it seems like the humidity level drops into the mid to lower 50% range. Should I just go ahead & add a few more handfuls of the eco earth or a few more 1/3 cups & mix it around again? I also was told once from a person who works at a reptile store to place plastic saran wrap over the top of the tank screen cover which will help w/ the humidity & moisture I presume. I do remember reading about this technique somewhere in one of the Tarantula books I have.

Defentley cover the top of the tank partially that helps a lot with the humidity.
If your T stops eating then dont offer any more crickets. Usually they are getting ready to molt. Their abdomen will get gradually darke 'til it's black.
Yes, 90% of T's lay on their back for the molt, makes it easier to slip out of the old exuvie (skin).

Keep in mind that changing the cage set up will also stress the tarantula. If you make a cage change or add/remove something, wait a few days to feed them so they get used to thier surroundings. I have notice after being held, I have to wait a day to feed them.