As of last week we noticed that the asynchronous tracking code was now the default code in our Google Analytics settings.
We have seen some reporting anomalies but are not sure if they have been caused by the new code or something else. We’re still waiting to get news on this change from Google (hey, thanks for not telling anyone, jerks!*) and we’ll keep you posted as we find out more.
For now, I would recommend updating to the new code, as it’s definitely not going to hurt anything in your reports. Note that this code does need to go immediately after the opening <body> tag – not before the closing </body> tag as all other previous code variations.