When a wheel bearing is shot it will make a grinding sound that usually can be felt as well as heard. The high pitched sound you're describing sounds like it might be you brakes. Maybe a wear indicator on the brake pads?
If the problem is a wheel bearing, yes it should be covered under warranty.
There's a TSB out for it. It's a problem with the brakes. Search for brake squeal and you should find about a 100 posts about it. Wheel bearings tend to tick when going in a straight line, they don't squeal.