Well if that is the case then when he went on Fox with Carl Cameron, right after he won the Iowa primary while in Houston, earlier this spring his eyes were black/brown.
One of the few times I have seen him where there were close up shots of him on tv.
It was very striking to see close up shots of him with black/brown eyes when his campaign ads show him with blue to green eyes.
I still think what you saw was probably a trick of the camera and the lighting. It is kind of like the red eye you sometimes see in pictures caused by a bright flash. I don't think he could get away with wearing colored contact lenses without everybody noticing and making a fuss over it. It is possible, but not likely.