I think Dennis's reaction was a cumination of things. Evidently Lewis was swearing at him in the early burn off laps when he was being told to move over. I think Ron knew that this would create tension with Alonso and Alonso's, puerile, move (or lack of it) was the end result.
Funny, though, that Alonso said that he waited for a further 10 seconds "becuase he was checking if the team had the right tires on" - a.) there was no radio traffic talking about that, b.) there's a big white stripe (or not) perfectly visible to even the driver with the current rules. Sorry Alonso, you're caught flat out lying there. He then had the gall to say at the end of the race that he was faster and Hamilton over the weekend, which clearly wasn't the case on Saturday.