"With Jonny's straight drive and Neil Wagner getting a touch, I just made sure I got my foot back. I looked at the screen and was pretty sure. I couldn't do much about it.''
There was still room to chastise himself despite the 167-ball, 228-minute stay at the crease, including five anxious deliveries before lunch.
"I was disappointed I got out as soon as the second new ball arrived because it exposed a new batsman. That's exactly what you don't want. Jonny and I had just got a hundred partnership and knew the next 10 overs were crucial. Fortunately our guys batted well to get a partnership together afterwards.''
The Yorkshire angle will get plenty of column inches and airtime but Root's nod in the direction of purists makes the innings more welcome. Sure, he sneaked in a reverse sweep at one point but his technical savvy and measured temperament make him part of the future shop window to the test game.
New Zealanders saw a taste of it with 40 and 71 at Lord's last week and at home where he scored 56, 79 not out and 28 not out in the one-day internationals. He can be a youthful assassin to bowling attacks.
New Zealand's Trent Boult acknowledged Root stymied their progress after they struck back to have England 67 for three at lunch.
"He played extremely well. He's got a good game plan and scores all around the ground. The wicket was pretty slow so we couldn't bounce him or look to push him back.''
The perception of Root playing shots all around the ground makes his wagon wheel curious reading. The reality is just two runs came in the traditional mid-off/mid-on `V'. Instead he made 55 between cover and gully while peppering 41 between mid-wicket and backward square leg. He gives himself time to play, uses the pace of the ball and doesn't feel compelled to dominate bowlers down the ground.
Root might present a youthful demeanour but one suspects that line of thought will be dispelled quickly with further cricketing dominance.
In a spot of, presumably, stand-up Twitter comedy, Kevin Pietersen tweeted: ``Today is historic. The first 9yr old to score a Test 100. Huge congrats.''
Root smiled when asked to respond: ``It's not something I'm too fussed about, I can't help it.''