Can an employer revoke the approved I-140

[Priyanka03]

Hi, 

I joined employer B within 4 months after my I-140 was approved through employer A. 

When I checked with my first employer (after 7-8 months) the said - we had send the request to revoke your I-140 as soon as you left the company.  However, we never received any formal notice from USCIS back.

When I am checking the online status ( Its been more then 1 year now)  it still says - Your I-140 was approved. 

Not sure if my I-140 is still valid or got revoked. How can I check?