My 42mm black sports band similarly updated today. From what Ive seen, the change to a more specific window seems to come not long before actual shipping, so I suspect well see these sooner than the window given.
Happened to both my white and black sport bands. At least it is less vague than "May" but thought they would ship earlier than the end of May. Oh well, no watch yet either, so it doesn't really matter.
I ordered the white band on April 19 and the pink band at 3:08 EST on launch day, and they both have been updated to the same delivery window. Kind of bummed that one was ordered so much earlier than the other, but no difference in their statuses. Here's to hoping they ship sooner!