Or it might be a strange mutation. The first ones were red and the new flower blooms are pink....did the new spike come from the same bulb or a different bulb from the first flowers?

Most Cyms when they reach a certain size, should have more than one spike when they come into bloom, many times maturing at slightly different times. Although you may not have seen the latest spike fully up in the foliage when you got it, trust me, it was there. The heat of your home just expedited it's growth and bloom.

As far as the different color - orchids in bud/bloom are transported from ideal growing, nursery conditions, ie light/moisture/temperature, in "sleeves" which protect the buds and flowers. They go through dark and often warmer staging areas. At this point, because of these conditions, the young spikes are hastened and most often the flowers, due to the lower light, come out a washed out color in all but the green and white shades. Ironically, these last colors are enhanced by low light.

When your plant blooms again in the proper bright light you should be growing it in, the color should be the dark color you fell in love with when you first bought it.

Beautiful, I like both colours on it.