Need help from creamcheez...

I am a F1 visa holder but it will expire this month. I has been working on campus for last several months, and can still work there even after my F1 expire. They have my name and SSN and pay me by check. I am on the process of changing to F2 (filed). Is there any way INS may investigate my employment while dealing with my case, or how dangous if I still work after the F1 expiration? I'll return China half year later. Really appreciate your kind help!!!