Kawasaki z125 high pitched noise at high rpm

Hi this is my first bike so I’m not sure if it’s something to be concerned about. When I get to a higher rpm about 7,000 the engine starts to make a higher pitched noise and it doesn’t stop until I go up a gear. This bike has done about 1,500 miles. Is it that I need to put more miles on the bike? I’m not sure. Thanks for any help.