I have been re-exposing my paper negatives with both incadescant and daylight. I have found that I have a fogged mottling appearance on the finished print.

Is this caused by the B&W paper development (Dektol in my case), or would this be caused by the re-exposure of the paper?

Would using an E-6 reversal bath be possible with RA-4 papers and/or would this be preventative?