Sqeaking front brakes

I did a search on this before posting, but couldn't find anything relevent.
So here's my story.

My '07 T-Spirit gave my partner a bit of a shock last week.
It started squeaking from the front right wheel. Only slightly at first just rolling away from a stop, but eventually (after a couple of days) it was constant, and getting louder.
So I take a spin out yesterday, and realise it sounds as if the brake pads are rubbing constantly on the discs.
She was with me in the car, and we had the windows down listening and she said that the left was also starting to squeak as well.
Back home, I jacked up the car and removed the front wheel.
Suspecting that the caliper(s) had somehow siezed, I removed the two bolts holding the caliper onto the mount.
I used to do my own maintenance on my vehicle when I was younger (couldn't afford a garage), and still do on my bikes so I recognise things that are 'generic' to most vehicles.
I saw that the caliper mounting bolts fit into pins that are inserted into the caliper carrier. These pins have rubber bellows signifying that they are supposed to move.
Well guess what! They didn't!
Eased off the bellows and pulled the pins. No, they weren't siezed; they were 'glued' stuck by the old grease.
A quick wipe with a rag got them clean, a small smear of new grease on the pins and we were good as new.
I pulled the pads while I was there and nylon brushed all the brake dust away as well.
Checked the other side. Same problem.
Job done, both wheels in under an hour, and then out for a test drive.
Perfect, silence again.
I like simple fixes.

On a side note, I read somewhere that the majority of 'normal' braking on a Prius is via the regenerative braking procedure, and only the last bit under 8kph (5mph) is done by the mechanical brakes.
This might have some bearing on why the pin grease hardened up (lack of 'use' compared to normal vehicles), but I'm only guessing here.
It could also be caused by it's age, and/or lack of a brake maintenance schedule. Again just a guess.