I have no idea, but here are some things to think about.

Have you looked for sucking insects like aphids or chewing insects like caterpillars, particularly on the back side and tucked into petals?

Have you have a lot of rain? Has it been particularly chilly?

It looks like a young plant, and they don't always behave quite like more mature ones, so I probably wouldn't worry too much.

The leaves look healthy, so I doubt it's a nutrient/fertilizer issue.

No, I haven't looked for insects. We had lots of rain but not as much in the last 2 weeks really. Weather has been warm for the past week. It is young. I also transplanted this in the spring from a shadier spot. I will do more inspecting tomorrow. Thank you!

I agree with gardengal48, it's the weather

Thrips like to eat color off of flowers, happens to roses and daylilies a lot.

Even when the weather is not off first blooms can look a bit different from subsequent blooms.