Wasn't there a sense of tension in like half of all episodes?

Hahah yeah. I thought it was just Gruber's personality. There were probably problems when Gruber slammed Readabliity as a scam while one of their investors is Jeffery Zeldman, another 5by5 host. He talked bad about it for a few episodes

I remember that episode and Dan seemed uncomfortable when John kept going and going about the topic. I don't know Dan personally, but I honestly think that he didn't like the fact that John called the "Readability guys" scumbags several times.

Or that he wouldn't like anyone saying that kind of stuff on his shows. I understand him.

I gotta say though, kudos to Dan for exercising superior patience throughout

Jeffery Zeldman gave Dan an interview on the latest episode of his show (#70, http://5by5.tv/bigwebshow/70 ), coincidence?