I would imagine redleg is only one way in which frogs can appear red.
I think what you have witnessed is simple genetic variation. My back garden pond has hundreds of frogs, many of which exhibit a deep reddening colour all over their body. They are all fit and healthy and I have not found one dead frog exhibiting the symptoms of redleg.
In fact when i was young there was a particularly large male frog, which was very red in colour, who always sat in the same area of the pond, and who i named (rather unimaginatively) Red. Red inhabited the pond for around 3 years before he died (i assume) from old age. He definately did not have 'redleg', and frequently mated year upon year (I am not into frog porn, he was just hard to miss as he stood out when doing it!!!). This is why i think there has been an increase in the frequency of red frogs in my pond, because old Red had been busy distributing his red genes :-)
Rest in peace Red