Mouth breathing = chapped lips?

I have used nasal pillows for the last six years. In the last month or so I have noticed that I wake up drooling more than I ever have and now I have extremely chapped lips. I know it's possible that I have become more of a mouth breather than I have been in the past. Would that cause my terribly chapped lips? At first I thought I was just dehydrated but after upping my water intake and no change in my chapped lips as well as really thinking about what could cause this, mouth breathing is all I can think of.

I used to wake up when I would open my mouth because the whoosh of air was annoying and would wake me. Apparently now it doesn't even faze me as I have been told sometimes in the middle of the night it happens that air is just blowing from my mouth. I have ordered a chin strap but am not sure it will help. Has anyone else suffered badly chapped lips from mouth breathing with nasal pillows? If so was a chin strap a sufficient fix? Id really hate to go to a full face mask.

My experience seems to be the opposite of what I'd expect but FWIW - I don't believe I'm a mouth breather because it wasn't evident through 2 sleep studies and 2 titration studies. No doctor or tech ever suggested using a FFM. And I haven't had any large leaks to give the impression that I might be losing pressure through my mouth. Long story short, I had trouble with pillows and thought I could no longer use them, tried a couple of nasal masks but got open pressure sores so I tried 2 FFMs (FitLife Total Face Mask, and Amara View). I'm now back to using pillows and small nasal mask. Although my lips do seem to get dry with the pillows or nasal mask, I had the worst dry mouth with the FFMs - to the point where I had trouble opening my mouth in the AM because it was like it was glued shut from the dryness, even with Xylimelts. All this is to say that a FFM may not help and may even make the dryness worse. Maybe try using something on your lips to help keep them moist through the night (Lansinoh?) and see if that helps.

I use a FF mask, but I have always had a problem with chapped lips. I use a chap stick every night before I mask up.

Dry mouth and chapped lips doesn't mean mouth breathing for me. When I start having a problem, I use Burt's Bees and Orajel for dry mouth. The only way to know if you are mouth breathing is to look at software at your leak rate.
The drooling could irritate your lips and possibly the chin strap could help that or you might want to look into a soft cervical collar, it might be a little easier to tolerate.