This sounds like cylinder drift and is not normal, no matter what any dealer says. Put a load in the bucket, hold up the bucket with a come a long or something similar. Remove the hoses from the cylinders and cap them with steel caps. Make sure they won't leak. Now remove the come a long. Measure how much the cylinders drift in 15 minutes and in one hour. Ask the factory what is acceptable. Compare and go from there.
Very rarely is this drifting caused by anything but the piston seals in your cylinders. I have a man lift here in the shop that hasn't been started in over 3 months. The cylinders have not drifted even 1 centimeter.