This from Mares:
Please be informed that we have discovered a quality issue on the O-ring assembled on the Nemo Air Quick Connector.
Under certain circumstances the O-ring can fail and consequently Nemo Air may start leaking through the Quick Connector. As a result, there is a continuous, albeit slow, loss of breathing gas. This situation could potentially lead to an accident, hence Mares has decided to issue a product recall. The solution already exists in the form of an O-ring of different material and hardness which can be retrofitted onto the Quick Connector of your current Nemo Air.
You can find out more from the Mares Home Page, where you can download a PDF with the full safety notice.