Anyone know why?

The last few rainbows that I have kept and eaten have different color meat.....Some pink,some white. Does anyone know why or what causes this? (And yes they were cooked thoroughly)I was thinkin about it and only thing that came to me was that maybe some of them (either one either way) were stockers and some were not but that doesnt make any sense to me because the places ive been lately are not the type of lakes or locations to have natural fish there, if ya know what I mean.......All these lakes are that ive been tohave to be stockers and stockers only as far as rainbows go.....I dont know....... What do you guys think??????