Is it normal for my rear brakes to squeek?

I took my car in to the shop last week and they changed out my rear brake pads because they said they were worn down almost metal to metal. The thing is, now the brakes are squeeking even more and louder than before I took the car in. My dad told me it's normal because it needs time to break in but how long is that supposed to take? Just wondering if this is normal to squeek for a whole week.Is it normal for my rear brakes to squeek?what it probably is is that they havnt cleaned the build up of rust on your brake discs, and as you say, the new pads need to bed in to the discs, but, I would take it back and ask why they havnt cleaned unwanted rust etc off discs, it is common practiceIs it normal for my rear brakes to squeek?depending on the material that was used for the brake shoes. that could be the source of the noise. this is the biggest complaint that i have seen since asbestos was dropped from use in the pads and shoes.