While making some masks from color negatives this morning I mixed up the sheets and ended up developing the color negative along with the B&W film and was surprised to see that the negative came out darker in the end than it originally was. I'm guessing this is a sign of poor fixing and that there was residual silver that developed out in the process. Is that possible and should I re-fix my negatives? Would re-fixing even do any good, or am I in deep ...um, trouble?

Man, what a bummer!