I'll take a shot in the dark. Not exactly dark, I can see your paint cans, and I know exactly why this happened to your paint finish.
You sprayed a hammered finish silver as your "texture" coat, correct?
That Rust-O-Leum Hammered Finish Silver paint has additives that causes the paint to resist binding, causing the paint to have the "textured" look, but thats not your issue. The Resin type used in "ROL" Hammered paints is a "Modified Alkyd", to put it simply it is an
oil based paint.
You then took that Black Night Metallic paint and sprayed over your Hammered Silver, correct?
The Resin Type in Rust-O-Leum Mettalic Black is a "Solvent Acrylic", and to put that simply, it is a
water based paint.
So, you sprayed a water based paint over the surface of an oil based paint. You didn't notice it cracking immediatly, thats becuase over time the oil will leech out the hammer paint surface, and before the black dried, it reacted with the oil, causing the "cracks".
My next guess is that you didn't sit and watch paint dry, so you came back and did the, ZOMG, WTF happened dance. Well, Now you know. Water based over an oil based paint does really funny stuff.
Thats not to say that you'd never be able to paint over a hammered finish oil based paint with a water based acrylic paint. But you really need to plan in advnace if you want to do that. You need to allow a few days for the hammer paint to cure first, and it is important to thoroughly clean the surface before spraying on your water based color coat. Any oil left will cause your paint to do funny stuff.
Need a the credentials to back up the explination, well I am Mechanical Engineer, the education gave me the ability to understand the technical reasons, but thats not exactly why I know. Having this as a paint rack gave me the experience to know a lot about spray paints, and how to cause purposeful paint effects like the one you accidentally had happen. This isn't even all of the paint, its just spray paints I use regularly...
P.S. Hammered finish paints typically require a few coats to get a noticeable hammered finish.
Good luck on the rest of your build, looking great so far.