I got 11" MBA today. I'm happy with it, but there's something that bugs me. The very top of the trackpad (approx 1cm or slightly less) does not register move up/down motion and taps at all. Is this normal? I can scroll left/right on top of the trackpad and that registers fine, but when I try moving finger up or down there, the pointer stays still. Taps also don't register there at all. Should I be returning this to the store for a replacement, or is this simply how it is with these glass trackpads?