Usually, when the FP is sent by FBI to INS, within 2-7 days, the message will be changed. But knowing INS' efficiency(inefficiency?), I wouldn't be surprised if they have got your FP from FBI and haven't changed the message.
My suggestion: Call the INS and speak to a person. Check with your imm. attorney before doing this. These kind of discrepencies happen with INS so do not worry.
Changing employer doesn't affect the finger prints process.
Apart from the finger print appointment notice you have got in the mail, INS doesn't issue any other notice for that(means any approval notice for FP).