I've often contemplated such a phenomenon, especially as it questions what is reality. I believe it is a foundation of quantum theory, that reality depends on the position of the observer. Does the real colour of the petals exist outside our and the bee's experience, or is reality dependant on who or what is doing the observing? And has the flower evolved both colours simultaneously to attract bees for pollination, and to please us, so that we take care of it (lost cause in our house!)? And is it just colour that changes with the observer? What about shape, texture and smell?
Interesting image for a Sunday morning!