This week's book giveaway is in the Agile and other Processes forum. We're giving away four copies of The Mikado Method and have Ola Ellnestam and Daniel Brolund on-line! See this thread for details.
I suspect that you created the hbm files previously and thus this message is saying that you haven't made any changes to the source to to warrant recreating the hbm files. You could try doing a Clean first. Or manually delete the hbm files. Or better yet, run the hbm utility from the command line.