Ok, I'll move it a little ways from the window. The plexiglass does leave room on each side, so it's not sealed at all. Hopefully the heat was causing it.

I didn't mean that I used the soil before, I meant I used the vase to cover the flytrap, I would turn the vase upside down and set it over the flytrap. The soil is new, so it should be good. Thanks
-Paul