Wow, that is a mystery! I did a quick internet search and wasn't able to find anything about bloom colors reverting over time. According to Veronica Read's "Hippeastrum, the Gardener's Amaryllis", H. aphrodite is one of the Japanese doubles developed by the Miyake Nursery. Read states that some of the Japanese doubles show a lot of natural variation in markings, in blooms on a single scape or on different scapes in the same year. So the question is, "Can there be this much variation over successive years?" In the absence of any other explanation, I bet that this is Aphrodite, which is not showing its markings this year for some reason. Three seasons from now will it continue to look like this or will it show its Aphrodite markings? Photo documentation is extremely important in this case. It you ever get bulblets on this one, it would be neat to grow them out to see their blooms.