well it depends on what you mean "curled"...if it curls up, that just means they are alert, such as at feeding time. If it curls a weird way, and is permanent, it could either be a kink in the tail or part bitten off and twisted by another littermate when being raised by the breeder. post some pics, itll help a lot more, so we can be more specific.
-----
~David - KDRKreatures
My Main Herps-
1.2 Bearded dragons (Ralph, Artemis, Cheech)
1.0 Veiled Chameleon (Chiquito)
1.0 Black Racer Snake (Chong)
2.2 Eastern Box Turtles (Athena, Mercury, Gizmo, Galapago)
0.0.2 Leopard Geckos (Nee, Unnamed)
1.0 Ball Python (Carson)
KDRKreatures-Home Page
My Email