If you were in a party that switched over to a different stage, then that stage is unlocked. Example, if you were in a Trial Forest party and the host switched to Kaze'Aze's Castle (doesn't matter what star) and started the game, then that stage (only 1 star) is unlocked.
Trickster Online - CujoEX/Sohei/HondoKitsune
Grand Chase - CujoEX
LaTale - Cujo/CujoEX/Sohei/Balsa
AIM: cujoexl - MSN: firstname.lastname@example.org