Here's my thought process, correct me where I'm wrong. It seems the human body has thresholds.
Examples: You lift too much weight, and the muscles and tendons risk serious injury, but otherwise they tend to rebuild stronger to handle more weight. Too much sun can lead to sunburn or worse, but moderate UVB exposure can lead to melanogenesis and increase protection to UV damage.
Do the lungs behave in a similar manner where a small amount of smoking might actually strengthen your lungs before reaching the threshold where you're causing severe damage? My guess is the answer is "probably/somewhat" but that there haven't been any studies since it'd be difficult to analyze and quantify, but maybe somebody has an answer based on theory.