Are you sure you....
lost all of the air? It's not uncommon and actually quite normal to hear air escaping from the pump as you unscrew the air chuck. However the valve core in the forks valve stem should be disengaged before he seal in the chuck. Usually the air you hear hissing out as you unscrew the air chuck is what is left in the pump and gauge escaping. Reconnect the pump and see if you have any air pressure at all. If not then yes you lost all the air. If it reads between 80 and 90 psi, then all you lost is what was in the pump. Also it is normal to get a reading between 5 and 20psi less, depending on the size of the air chamber, than what you had when you disconnected the pump after filling. This is because when you reconnect the pump it requiers air from the air chamber to refill the pump and gauge. Any time you have a container of a given volume at a given pressure, if you increase the volume of the container, the pressure goes down. What you are doing when you connect the pump is effectively increasing the volume of the air chamber of your fork. So you loose a little pressure.
Anyway, if you are loosing all or most of the air from the fork when you disconnect the pump, there are two things you can do. The first is check the valve core in the valve on the fork and make sure it is fully seated and snug. You'll need a valve core wrench for this. You can get one at an automotive parts store, or just run it in to your LBS, they should have one. Takes about 2 seconds to do. The second thing is try a different pump. Some of the cheaper pumps out there have poorly designed air chucks. The pin inside the chuck that depresses the valve core as you screw it on may be a tad too long and doesn't disengage the valve core before the seal between the valve and chuck is broken. This would cause air leakage from the forks air chamber. If it's bad enough you could certainly loose most or all of the air you just put in the fork.
So before you get too crazy, double check a few things. :thumbsup: