i had a similar problem a few years ago with my first gecko, i've been told its alot more common and more fo a problem with babys. i tried moss for a while but didnt care for it, i now use torn paper towls(3-4 inch long peices) you can use just a single paper towl and lay it flat, but i've found they like it better when its more fluffy like a bed, so thats why i tear it us, their cheap to replace and most people already have them handy anyways.

i also prefer them because you can use a box with the hole on the side and it rarley gets dragged out like vermiculite always did for me.