Once again...baffled!

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I have a Phal Maraldee 'Brother' which was in bloom when I bought it last year. The blooms were yellow with reddish markings. This year, it's got a number of buds on it and one of them opened yesterday. It is more green than yellow! I looked it up on Wildcatt to see if I could get which color bloom was the "correct" color but found that the descriptions of awarded plants vary, mentioniung both colors!
Why would this plant bloom in a different color from one year to the next?
Here are pics (first is last year's bloom, then this year's) for comparison...