Or a mixture of the above reasons, of course.
Something completely different is that I am 1 of the first bloomers in spring so I will announce spring / summer for you.
During the day when it's hot, I open my flowers but in the evening when it cools off I close them again quickly. In fact, if it's not hot enough during the day I won't open them at all!
But wait until the end of May or later before you start picking and even then, don't pick everything yet! The biodiversity and bees will be very grateful!