My chest X-ray indicated my lungs are hyper-inflated. What causes this? No asthma & non-smoker.

Smoke-damaged lungs. Hyperinflated lungs implies smoke-damage, which leads to emphysema, which leads to copd. If you haven't already, stop smoking -- you will live 10 years longer than your 42yo friends that keep smoking! the inhalers you're using are #1 steroid for lung inflammation, and #2 bronchodilator for coughing/wheezing. With luck, after 1-2mo you can stop #2 and maintain on #1, assuming you can quit smoking.
Maybe Nothing. Slim healthy people are sometimes able to take such a good inspiration that their lungs appear, "hyper inflated"! in the absence of any history or symptomatology of lung disease or smoking, i wouldn't worry. Some people may be congenitally deficient in Alpha 1 anti-trypsin and develop emphysema but they would also be symptomatic.