What explanation is needed, the O/S as of 8/19 was 343.5M per the 10-Q, same as what you listed
The brokerage houses are no better at telling you the float than I am. They simply use the public filings that are available to everyone, they do not have any special "inside" info.
But any increase to the O/S would be due to convertible debt as laid out in the quarterly filings, but the O/S appears unchanged so everything seems great to me.