Ok, so I started thinking (usually dangerous when I do that), and the ammonia explanation made sense to me, until I started thinking about cigar leaf blends. I’ve let plenty of those go out before, and relit them. No issues. Not enough cigar leaf to matter? Different kind of cigar leaf with less ammonia (or ammonia production potential)?
It's a lower amount of cigar leaf. It would have been blended to ensure a neutral pH so it isn't overpowering which would most likely entail the addition of flue cured leaf, but could also include addition of citric acid and/or sugar.
I've smoked trimmings from cigar rolling in a pipe and it makes your head swim.
The body, especially the lungs and kidneys, is constantly trying to remove acid in order to maintain proper blood pH. That's why we breathe out CO2. We absorb alkaline more easily through lung tissue and mucous membranes, etc. So, even if nicotine level is the same, an alkaline smoke will result in quicker nicotine absorption. That's why snus is made alkaline with carbonate.
Smoking tobacco is blended with this in mind; Virginia which burns acidic and burley which burns alkaline. Too much burley and its too strong. Too much Virginia and it burns the tongue (with formic acid vapour). Cigar blends are essentially the same, except in this case, the alkaline tobacco is not burley, but cigar filler.