There is a very good reason why we say to change this everytime you replace your timing belt!!!!
This pulley is basically nothing more than a big giant sealed bearing... Eventually over time, the grease inside dries up, mostly from constant usage & heat. When the grease dries up, the pulley gets noisy.. If it stays like this long enough w/ no grease, then the pulley will eventually will seize!!!! Am betting this is what happened.
The other scenario, is when one of the timing belt pulley seals (crank, oil pump driveshaft, or 1 of the camshaft ones) is leaking oil like a sieve. All of that hot oil flying around in the timing belt housing will get inside the pulley & dissolve all of the packed grease. Pulley eventually seize's, due to lack of lubrication. Almost had this happen the 2nd time my front seals started leaking & soaked the timing belt w/ oil. The belt only lasted about 30K miles. The pulley did not seize, but if you spun it, it was one NOISY MOFO.... All the grease inside of it had dissolved.
So yes, replace the pulley on every timing belt change... AND replace the pulley tension spring as well, the spring will lose tension eventually.