Sort of. A Google search for "kept my countenance" turned up a bunch of hits, all 19th Century, and all in cases where the speaker, in reaction to the words or actions of another, was avoiding changing facial expression for tactical reasons. Since this is an internet board, not a cocktail party (much as it sometimes seems to be), and we weren't able to see that dtb had theretofore been keeping a straight face, using "countenance" as a noun seemed somewhat out of place.
I think dtb's been reading too much Austen lately.
tm
