For privacy reasons, Apple should *never* ask you for your password..
It may be normal to Apple, but its definitely not normal to me, and will refuse....
Even though this doesn't extend to repairs, it should.... As i never give out my password to anyone... not even Apple... If you have to replace a battery u don't need a password,, all u gotta do is switch it on to see its ok..
If Apple tells u when u pick it up, they can't unlock it, then at least u are there. Ask Apple for the phone and u unlock it, hand back to them.. I never give my unlock code over the phone, or on any form ever.