All my tools have been in storage for over a year including the compressor. I was messing with it yesterday and found that it is still under pressure. Nothing leaked for a year. There was no pressure gauge because the regulator died a long time ago and I had it piped to a regulator on the wall. I just had a quarter turn valve on it. When I opened the valve, I heard a gentle 'pssssssss'. I have one of those Harbor Freight auto bleed things on the drain and that didn't leak.
I'm really impressed. Not bad for a Husky compressor bought 10 years or so ago from Home Depot.