I think you 'winning' was exactly the reason they didn't particularly like it. In you agreeing to charge by page and not time, they very well may have thought they were having you. In the sense that they believed it to be a slow process and by you not charging per time they were getting a deal by possibly paying less if you were slow.

You learned about "value"

They had a difficult problem (from their perspective) and they saw you easily solve it. This changed the "value" of your work in their minds.

http://www.snopes.com/business/genius/where.asp

Dale Carnagie wrote that in order to be successful, try to make the other guy feel like he's a winner, even if you got the upper hand. I would have kept the amount of automation under wraps!