Before I got my dragon, I could have sworn the Habba Huts were finished with some kind of sealer.
After I got him and went looking for one, all I found were the unfinished ones.
I don't really know if they changed, or my memory was/is faulty. I wound up returning the one I bought.
I know some people have them and claim no problems, yet they could be off-gassing VOCs into the enclosure, depending on species, age, and other factors. Sealing them yourself is one option other than replacement. I tend to be a "better safe than sorry" guy, so you should probably dig into it on your own and come to your own conclusions/decisions.