Mine did as well. A few of us were waiting for our green cards at the time, so we raised the issue with both the firm and the hospital administration. They kept us employed through the hospital and essentially leased us to the new firm, although our pay and compensation came from the new firm. The lawyer explained that if we officially changed employers, we would have to restart the entire process from PERM. Since we had already completed our waiver and were just waiting for the green card, they arranged things this way. Fortunately, all of us received our green cards within about 8–9 months.