“After-midnight” as adjective

Question

A recent CNN report reads:

In an after-midnight session the U.S. Senate passed a bill Saturday ...

Google returns few results for after-midnight, other than references to a certain horror film, (another earlier film), a Clapton song, and things related to one or the other of these.

Q. Has after-midnight been used in this sense in popular writing? Will it be considered ungrammatical/ incorrect to do so?

CNN uses it again down the report "In a previous after-midnight vote, the Senate overwhelmingly passed a non-binding resolution ..."

Answer 1

There's nothing ungrammatical or incorrect about it. It's simply a time adjective and can be replaced by late or very late. Normally, the US Senate doesn't stay up so late working, only partying.

The origin and first recorded use of the expression is probably something you'd want to ask Michael Quinion about.

Looks like a perfectly normal adjective to me.