I also wonder if certain microclimates and soil composition can affect both plant/scape/bloom size and also color. I have no idea if this is common in daylilies or not, though I certainly have some plants that have not gone "exactly by the book". Guess they never read that chapter!
It happens with other perennials, so.............? I have a gaura that I know was labeled "Whirling Butterflies" and another "Siskiyou Pink" (not sure about the latter spelling). They both were bought at a very reliable perennial nursery. Supposedly they reach between 18-24 inches in height. Well, mine have gone over 3 and up to 4 feet some summers! So? No idea why. Plus, they throw seed like mad.
Ginni in WI