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 ..."