Shooting a 6 inch target with an unfamiliar (and by all intents and purposes; a new) gun with iron sights at 100 yards straight out of the box = a good gun, and good shooter.
That's the main reason to spend time behind the trigger of any gun is to familiarize yourself with all the intrinsic details and nuances of it.
Very few people I know can pick up a new gun and shoot bullseyes with it on the first few shots. That takes time.
So what. You had to adjust the sights a little, but that's what you were supposed to be doing to fit YOU.
The end result is you were placing bullets in the zone, and that's ultimately the end goal. Nothing to drop your head for in my opinion.