I'm not sure about the bleeding issue. However, I want to recommend Michael Miller's Jet Black fabric if you want the truist (is that even a word?), richest, deepest black. The hand of the fabric is much nicer than Kona black (which I have also used), which is another benefit.
What I recommend is testing a small square of the black fabric first. Drop into a glass of water and leave for several hours to see if any dye bleeds into the water. After that, take the dampened fabric and rub it against any whites or light-colored fabrics that will be in the quilt to see if dye transfers that way (this type of dye transfer is called "crocking"). If the black fabric passes both tests, I wouldn't hesitate to use it without prewashing.
I do, however, always take the precaution of washing the finished quilt the first time with Synthrapol in the largest laundromat front-loader I can find. That takes care of any small bleeds from all of the fabrics in the quilt.