I recently had a chest Xray for a suspected broken rib and during the xrays I was asked to take deep breaths. When i got the result it said slightly hyperinflated suggestive of mild air trapping. I did smoke through high school and quit about 2 yrs after and im now 29 6ft and have allways been active with a good diet.
Chest X-ray is always taken with a deep breath. If IR still shows hyperinflation, it could be because of smoking. But do not worry as you have no symptoms but continue non-smoking status and do deep breathing exercises