I would like to know if Asylee have to appear for an interview before adjusting status to the permanent resident.

I am asking this because my friend became asylee six years ago. He filled his I-485 application five years ago. Right now, he got letter stating that he has to appear for an interview before immigration officer for his status adjustment. Is this normal? Or something is wrong with his application somewhere! As far as I know, he has not been arrested or committed any crime.