Is “go all coy over stg.” an idiom or simple combination of words?

Question

I found the phrase “go all coy over reports “in the following sentence of Washington Post (May 12) article introducing CBS’s reported deal with Ashton Kutcher in replacing him Charlie Sheen as the leading cast of its sit com, “Two and a Half Men.” Apparently “go all coy over stg.” looks like an idiom. So I checked usage of ‘coy’ in English Japanese dictionaries at hand and Oxford Advance Learners’ Dictionary to make it sure, but none of them carries the words, ‘go coy.’ Is “go all coy over stg.” an idiom, or simple combination of words?“Ashton Kutcher has suddenly gone all coy over reports that his entourage is putting the final touches on a deal to have him replace Charlie Sheen on CBS’s “Two and a Half Men.” Kutcher’s finally got something he could tweet that we really want to know about, and now he clams up. Geesh!”

Answer 1

It seems to me that “go all coy” may simply be a regular phrase of rather colloquial style, as in “go all humble” or “go all holier-than-thou”. “Go all coy” in that case would mean to act seductively secretive, trying to encourage interest while at the same time ostensibly trying to discourage further effort toward something.