Why was it undair? The umpire was wondering if there was an inside edge so went to the 3rd Umpire. There was no inside edge so he was given not out. That's when India had to ask for a referral for LBW and he was given out. India would have asked for referral if the umpire had not given him out by himself anyways.
What I thought was a bit weird was that once they saw there was no inside edge, why did they not check for LBW themselves. I mean, when a batsman asks for a referral challenging say a LBW decision, they dont only check for the LBW, they start by checking if a bowler has over-stepped.