Once again, I'm a noob and this is my first bike. I'm still having licensing issues (joys of the military), so the bike has been sitting in the friggin garage for the last couple of days. I've started it about 5 times and let it run for a few minutes each time, but later in the evening - probably 5 or 6 hours after running - the tank makes an audible, short high pitch whistling sound about every 3 minutes. It stops once i pop the tank. Is this an issue or is it normal? I know pressure has to be released from the tank from time to time, but i figured this wouldn't be an issue as it doesn't even have a mile on it.