I have a batch of 500ml of Kodak C-41 Flexicolor that was used already to develop 6 x (135-36 each) rolls. (3 cycles of 2 rolls each). All good so far. After that, I saved the developer in its dark glass bottle with no air all the way to the top. (I used marbles). It's been sitting there for about a month now, maybe a little more. I have now 1 roll of BW400CN chromogenic C-41 (B&W) 36 exposures. Is it ok to process in the used developer or should I toss the developer by now and freeze the roll until I prepare a fresh batch. I figured because it is B&W chromogenic , I wouldn't worry much about color crossover. thanks for opinions.