Rajiv and were compiled and reported by our editorial team from comments and blog on immigration.com
See clip from Attorney Rajiv S. Khanna's conference call video that addresses this question.
I don't see any problem. The reason being, that payment even though they are paying you after you left the company is not the violation of your status. It is reflective of the amount already earned. While you have H-1 with these folks you earned these amounts. Now, 1099 usually a bad idea but in your circumstances I don't see it as problem. Usually you can only do W-2 but in this particular case I am not quite sure how USCIS is going to look at it. What questions they are going to ask you.
But I can tell you this in the ultimate analysis after you have responded and made clear that , the money given as part of a bonus which was earned by you , you had a H-1 with that company . So it's not a new work. I don't think you will have any problem. So, legally you are in good position.