I recently purchased a Bach Strad 37 late 2011 model; it is my first professional trumpet. I have only been playing it for a week. With that said however, I'm finding a problem with it. Whenever I play a first-space F, an airy sound accompanies the note that I cannot identify. The same occurs with F sharp, and the G a little bit. It becomes really obvious when playing second-line G when I use the alternate fingering 1&3, and I am not understanding why this is happening. The problem seems to be confined to these three notes. Is it a problem with the trumpet and should I consider returning it within my fourteen day trial period, or is this normal? Thanks.