From DMM's website:
"DMM International has identified a raw material problem that may affect the strength on certain models of the Dragon Cam in size 6 (Product Code A7056A).....
..... The units affected were made between the 28th April and the 30th June and there are 604 units in the market that could be affected. The affected units have one the following serial numbers. The serial number is located on the back edge of one of the two centre cam lobes. If you own a Dragon Cam 6 with a serial number listed below then you should immediately discontinue all use of this product."
Here's a link to DMM's website (including the list of serial numbers of affected cams):
They've also posted a pdf which goes into a lot of detail about the recall. Here's a link to that too:
To re-iterate, if you think you have one of the affected units, you should discontinue all use of the cam, and contact DMM.