I entered U.S from Company A.
2 weeks after entering U.S, I joined Company B on H1b Transfer, worked for 6 months.
joined the Company A on Previously approved H1b. Worked for 1 year,Company A Filed my Labor and Labor Approved.
joined Company B on previoulsy approved H1 for 3 months.
Joined Company A, with the new H1b(Tranfer). Worked for the company A for 3 yrs. got I140 approval in 2008, 485 was filed in Sept 2007.

Joined Company C(Filed AC21) from Feb 2009.

GC Case is now transfered to NBC, status of approved I140 flipped to "Initial Review"

FYI: My approved I140 was not revoked by Company A.

Will there be any issues by changing the employer's on previoiulsy approved(Valid) H1b?

My Q. is Why my Case is transfered to NBS, why did they open my approved I140.