It could still be the wear indicator. As the pads get worn down, they'll make noise even when you aren't hitting the brakes, and it usually starts making noise when you turn one way or another.

I'm not saying it's the brake pads for sure, but it could be.

As far as the spark plugs go...in 2000 they switched to platinum plugs that ideally last 100k miles. So it doesn't hurt that they changed them, but if they changed them with copper plugs, you don't want to wait until 100k to change them again...they last about 30k miles.