Yep, perfectly normal.
By the way, if it makes that noise after the bike has been ridden some distance, it is a partial vacuum and not pressure inside the tank- the tank is sucking IN air, not releasing it. After the fuel tank has been filled with fuel, and the bike ridden any significant distance, the fuel is used up and the volume inside the fuel tank would be (and is) at negative pressure. If the tank was not vented it would crush inward due to the vacuum created by the pumping out of the fuel, not bulge outward due to internal pressure. Google 'crushed motorcycle fuel tanks' and look at the photos of European bikes that have had fuel tank valve failures and you will note that they are all crushed inward, not bulged outward.
Brian
When I park my 2009 in the garage after riding, I hear a hissing/air releasing sound from the gas tank that goes on slowly until all the pressure is released. Guess it builds up pressure during riding. Don't know anything about check valves or purge valves with the fuel system, but I read the only release area is the gas cap. So there is maybe a vent hole in it? If so maybe mine is blocked with dirty or something?
Does anyone else have this sound after parking?
Any other comments about venting and my situation would be helpful. Thanks.