1991 Honda Civic LX, 143k miles here

I replaced my front brake pads with quality ones last year about this time
and 16,000 miles ago. I have just completed a trip through two mountain
ranges, each not more than about 6000 feet in elevation. I tried to use my
engine to brake as much as possible. Now, after driving awhile each day,
either my front or rear brakes or both are squealing when I hit them even
lightly.

Would rear (disc) brakes squeal?

Could I have worn my high quality front brake pads down already? Might they
simply have become glazed due to a lot of use on long, steep downhills? Is
it okay to drive with glazed brake pads? (IIRC, it is, as long as one can
stand the noise. Will it go away as the glazed surface wears away?)

I know brake pad wear is very much a function of driving habits and not
mileage. But since I have never gone through a pair of brake pads this
quickly, I am baffled.

I will be removing one or both front wheels tomorrow to inspect the pad, but
comments today are welcome. People who drive in mountainous areas: Your
experience with brake pad life is welcome.