Brake foot valve seems weak in my 07 peterbilt 357 triaxle.

Ive recently made a pretty big jump up from a 95 mack r model up to my new ride a 2007 peterbilt 357. Im pretty new as a driver and these two trucks are the only two I have ever driven regularly. Anyway the problem I am having is in the peterbilt im now driving it seems like the brake pedal is much lower than it was in my mack and it seems much more difficult to apply light pressure to the brakes because with the pedal being low to begin with there isnt alot of travel room between light pressure and heavy pressure. So this may be a dumb question but is it possible for the foot valve to get weak and creep down? The brake application gauge says 0 when im not pressing it and when I do press it the gauge reads higher the harder I press and goes back to zero when I release it so its still fully functional but its just seems way more difficult to apply only light pressure than my old ride and when you look at the brake pedal in relation to the throttle pedal you can visibly see how much lower the brake pedal is than the gas pedal and in my mack the brake and throttle were roughly the same height when in their resting positions. I noticed these things the first day I drove the truck but just thought I wasnt used to the new truck but its been three months and I still keep locking the brakes up every once in awhile by accident because of the brake pedal travel span being so small between a tap and a stomp so if anybody can shed some light on what possibly could be the issue I would greatly appreciate your input. Thanks in advance.