Interesting to see if the eye changes keep happening, or if somehow they were perhaps not lit with lighting when you saw them last.
In rats and hamsters, there is an eye color called ruby. Basically it looks black until a light is shined near them, then they look a dark red.
Here's a pic of an odd eyed rat so you can see the difference. (Not mine.) One eye is pink (right of picture), the other ruby (left of picture.). This was taken with flash to show the difference more clearly.
A pic of a black eyed rat with flash to show the difference better.