…. or is there a honest to goodness glitch in the way browser shares are counted?
There is indeed evidence that IE browser share has dropped at the expense of Firefox over recent months. There is some evidence that there are problems with the way in which different versions of IE are counted which could be screwing up the stats. Regardless, Market Share by Net Applications, the service which provides a monthly market share assessment, has failed to produce the July 1 results claiming that the data are under review.
Can you say … “Confirmation Bias?”
Some details of this murky situation and links can be found here.