Is it normal for inflatable boats to lose pressure over time??? I have a 1 year old AK Series 420AR and I have to pump it up every time I use it. All the chambers lose pressure evenly - not just one chamber. All the valves are closed and there aren't any poke holes. The last time I used it was in August and now all the chambers are about 1/2 to 3/4 full. Is this normal? I've only used this boat a few times. What should I do?