Please note that the first service visit, 1k-->3k, only does a diagnostic check and Q&A with the customer. When I had a power lift gate issue and went back to the dealer, they checked the diagnostics [computer] to be sure there was no issue there. Thus, when you went back in, what they did was to check the computer for any stored codes to see if anything was amiss which might be contributing to your problem. Part of checking the liftgate function would include looking for any stored codes in the computer. Naturally, they read whatever codes were stored - i.e. the 1k-->3k service.
Actually, they did not do anything TO your vehicle.
Actually, they did not do anything TO your vehicle.