Not sure about Kodak RA-4 chemistry, but Tetenal and Photocolor recommend replacing 30% of the used chemistry with fresh, for replenishment with each print.
It does sound like a faint possibility of "carryover" - Bleach-Fix into the Color Developer. How are you washing the prints? I normally wash 6 x 30 seconds in the CPP-2. That should be sufficient to flush out the tank and processor.