Question about hard lemonaid

OK so I have a few experiments going in some 1 gallon glass jugs, one being some hard pink lemonaid.

Everything seems to be going smooth except it is losing its color, kinda turning brownish, is that normal? should I be concerned or something?

The ingredients I used were 2 12 oz concentrates, that didnt have preservatives in them, 1.5 lbs of corn sugar, and about a gallon of water, heated it all up, etc.

Well, I don't know if this answers the question exactly but,

I make a hard cider that the wife loves very much the same way. Apple Juice and Apple concentrate base with some good fruit juice for taste, tons of table sugar, and yeast of course. These ciders turn out dry, and usually a very pretty pinkinsh/red (cherry or cranberry flavor).

My only guess for your color would be maybe a citric acid reaction? As always my advice esp. for an experimental brew would be RELAX. Give it a taste when it's done and see what happens.