Clones preflowers?

Guys please assist me here. I have some clones rooted and everything but I'm not sure but it looks like some of them showing preflowers?
And they sure look like preflowers not calyxes.
Is this possible? There top clones from a 5 week vegged plants.
Thanks guys any feedback will be greatly appreciated.

Clones are 100% mature plants. Pre-flowers are normal.