Cottonmouth: What is it and why don't I get that effect anymore?

Back in the 80s when I first started smoking, every time I smoked I used to get cottonmouth, and usually what I smoked was some schwag from Mexico. I quit for many years and started smoking again a few years ago, and now that I have access to a wider variety of cannabis these days, it hit me that most of what I smoke now does not give me the cottonmouth effect that I remember from my early days where I could barely spit lol.

Have any of you you noticed this or is it just me? I know I'm a little weird, but I actually rather enjoy that effect and miss it.