By Daniel Moxon Adrian Newey hinted infighting at Red Bull was indeed a contributing factor to his decision to leave the team. The 65-year-old shocked the Formula 1 world this week with official confirmation that he is leaving the team he has served since 2006. It comes after months of unrest behind the scenes at Red Bull with team principal Christian Horner in the thick of it. In Miami on Friday, Horner had insisted that Newey’s decision to leave was “absolutely not” because of the infighting. “This has been coming for some time,” the 50-year-old asserted. “There was discussion pretty much 12…