Is it supposed to make that noise?

[Julial1345]

I'd been using my Canon EF 28-135mm f/3.5-5.6 IS USM lens for about 6 months when I noticed a kind of grinding sound coming for the IS when I push the shutter button half way. I sent it in to Canon as it was still under warranty. They sent it back saying they aligned, cleaned, and restored everything to factory specs. If there same problem reoccurs, send it back. The first picture I tried to take resulted in the same sound. I don't want to send it back right away, because they say they fixed it. This makes me think it may have been making this sound all along and I just never noticed. I'd feel stupid for returning it again for something that may not be an actual problem. Do Canon lenses make noise while the IS is doing it's thing or is this really a faulty lens that should be replaced since they couldn't fix it the first go around?

(By the way, I'm positive the sound is coming for the IS, because if I simply switch the stabilizer off then it is impossible to recreate the sound.)

[OsmosisStudios]

The IS does make a bit of noise when it's running: sounds almost like running water.