I also had the same failure, just over a week ago. I'd put in about 2000km on my Bryant with the belt (I switched to a chain for a while and then switched back.) Mine failed just pedalling hard to make a traffic light, luckily I was only a couple of blocks from my office. Ironically while I was standing there by the side of the Hornby Street bike lane wondering what the hell just happened, a couple of people came to ask me about the bike.

I mailed carbondrive@gates.com and got a reply within 24 hours, saying they'd replace the part for free, so you might want to try again. I did include a picture of the sheared part, so that might help.

I'm guessing Gates didn't recall the part because there was a hope that the failures only occurred with heavier riders, and that most parts wouldn't fail. But if true it does seem that hope was misplaced, I'm only 170lbs, though living in North Vancouver I am grinding my way up hills pretty frequently - but it does seem likely that all of these sprockets will fail eventually and probably sooner rather than later.