The hydraulic rams that control the slides are basically a closed loop of oil that is open when you press the slide in/out button. If your rams are creeping, my guess would be the hydraulic valve has a bad seal and is letting pressurized oil pass to the other side. The shop should be able to order a new seal kit.
I would call Lippert directly and I bet you get more action than letting the dealer handle it. They should be able to make a repair recommendation as to replace the valve or rebuild it.
Good luck,
John