That's actually correct - 'an' before a sounded 'h' is a style issue in American...

ajhit406 · on Sept 1, 2012

Yeah I was just going to comment on this too-- "a" vs. "an" actually has to do with pronunciation, not strictly words that begin with vowels.

Maybe the author is Irish =)

astrodust · on Sept 7, 2012

What's peculiar is that "a house" or "a hose" is given to be correct, but "a honour" or "a hour" is not.

It's probably that words with a more French origin, where the "h" is subdued, require "an" where the harder "h" from more Germanic words does not.