Well, it only took one hour but they fixed it.
Or so I was told.
When I locked then unlocked the door, it took 2 pulls of the handle to open to door.
Unfortunately, I was already back at work. I went there during lunch (it's a good thing to have 2 dealers in town, and I work by both of them !!), so looks like I go back again tomorrow....
I don't think the mechanic knew exactly what the problem was. If the doors were unlocked, it only takes one pull. If the doors are locked, then I unlock them, it then takes two pulls. Any door openings after that takes only one pull. I explained it to the service tech, he tried it, confirmed it and wrote up the service order.
The mechanic said it only needed a little lube.
They were busy, I was running late, but I should've stayed there and tried it a few times.
Oh well. At least the service center is really plush (spoiled Mercedes owners....

) and has free wi-fi so I got a little work done (and free coffee, water, etc.).