I would agree with TXHRGuy. Since you know about it, I would ask to see a copy and pass it by legal counsel. I would also check to what your state/circuit court precedents are in NCA court cases. I have known companies to not only sue the ex-employee but also their current employer (not that they have won by any means) but if they can bring you into the suit at all, they will try.
What state are you in? Is the other company in the same state? There was a case a while back (Palmer & Cay v. Marsh MacLennan) where the employee had a NCA in NY. He then took a job in Georgia and sued MM to get out of the NCA since it wasn't legal under GA law. He won and this case set some precedences. Actually his company is the name on the lawsuit, not his. So they won. But he was also brought in as the President of the company. I doubt your company will want to fight a lawsuit for this employee.