Pics are worth a thousand words.

 

Could be salt. That would be my guess.

 

If it was salt it'd be everywhere, and everything gets washed down after every trip.
It's just two of the seven rods last used that got left on the porch.

 

if it's oxidized, vinegar will clean it up.
if it's mildew, bleach will kill it.
but don't mix vinegar and bleach. it makes chlorine gas.

jack

 

Comes back as in you don't see it anymore? If so, it's moisture getting under the epoxy/finish coating.
2 ways to cure it. Don't leave it damp for extended periods or refinish/rewrap.
I'd stick with the first cure.

 

Same thing happened to my Rod the other day my dad sanded it down with 800 /1600 grit sand paper and then refinished it. It came out perfect. This rod was about 20 years old (Kennedy Fisher 7') and I think the apoxy had just worn down, it got rained on and was wet for a long period of time. The entire rod kind of had a milky look. Not sure if this helps but good luck getting it fixed!