Normal
My Zilla micro habitat developed a similar bow at the top and I never really liked how the lid lifted up, so I rehoused my G. pulchripes into a somewhat shorter enclosure with a sliding magnetic top. I think she is getting somewhat accustomed to it. She has removed all of the webbing she put up blocking her hide. As for the Zilla, I plan to plant several succulents in it with my regular substrate just to see how they fare.