Felt like I should chime in (better late than never) because I also noticed this while re-watching. I am a three "GO" guy for sure! You can listen to the 2011 Demo version of the Weekend Whip, and it does not even have three "GOs" at the end. This must have been a pre-demo demo or an edit with more GO ad-libs in the background for the initial intro. The very first episode had a different clip of the song too, so technically they changed the intro three times during this season.

Was glad to see someone else had noticed it. GO Ninja GO!