VERY UNLIKELY. Sounds more like there is a small drain on the system and those can be a nightmare to find. Which is probably why the dealer didn't want to have to try and find it since it can sometimes require tracing the entire wiring harness which can take hours. The first thing I would check is the brake light switch. If it sometimes hangs up after you leave your car then it will drain you battery eventually without you leaving anything on. One way you can check your circuits is to place a meter between the positive battery terminal and the positive cable (disconnect the battery from the cable) so you can pull out all the fuses and slowly replace then one at a time to see which one draws power (and how much power) with the system off. Most CPUs on cars are either in the central console near the driver's right foot of somewhere in the floor panel or kick panel. Look in the manual and find the CPU location. If the CPU (car's computer) uses a lot of power you would be able to measure the amount of power it uses (in amps) with all systems shut down. Don't forget the door switches and overhead light will draw power when you are working on it with the door open (disconnect the fuse or bulbs).
If you disconnect the CPU for nine days but leave the battery connected it would tell you whether the power drain is or goes through the CPU. CPU disconnected and off for nine days and then connected and the car cranks then it would be either the CPU or some system controlled by it. That is where removing the fuses can be helpful as with all systems off when you notice a large amp draw you have probably found your issue.
Northern Tool makes a battery disconnect switch for less than $10 which could be installed inside the car where it would isolate the battery when the car was not going to be used for a long time, thus preventing the power loss.
My gut feel is either your interior light, dash lights or brake lights have a bad switch which you might not catch unless you were looking for it. Keep in mind that it is common practice with dealerships to minimalize difficult to repair problems so that a customer will not force them to loose money on many hours of labor on a repair that they can not charge that much for.
Good luck,
Kaiser Willy,
Good luck,
