I had blood work this morning and the tech took the needle out while drawing blood. (was still half in) within minutes my arm swelled, knotted and turned a purplish color. i have history of blood clots. should i worry? been using warm compresses?

I wouldn't worry about a clot forming that would travel in your veins to cause problems in your lungs or anywhere else. These are instances where the point of needle entry will leak into the surrounding tissues and stain the skin. Any clot there is outside the vessels and doesn't travel. The blood breaks down and the body re-cycles its components for later use.