That is actually a terrible idea, as the client may actually be slow, and the other abstractor with work from them might have been doing it all along without your knowledge. It is not like a client is obligated to tell you everyone that they have doing their work.

Further, what are you looking at another abstractor's work for?

Brush it off, and chances are if you are not to emotional about it and keep a good repor with the client you will see work again...