It was 100% legit (albeit momentary) confusion as I just happened to see the Google Books update with a completely new icon and name alone on the My Apps page before I heard the news elsewhere. A few minutes later I also got the update for Google Music and I looked into it. Besides the weird "play book/apps" convention, I actually think this a pretty smart branding move for Google overall.
You actually thought that, or you came up with that as you were deciding to reply to the thread?