I'm sure its not a massive problem, but it shows a lack of care.
For a bit of balance - the person who served me was really polite and had a very helpful attitude. She even gave me a bottle of G13 coolant for free, as she said sometimes there is an airlock and the coolant level can drop.
I guess that's why they overfill, to stop the coolant light coming on and people returning to the dealership.
I've sent them an email explaining, and highlighting that there maybe a training / supervision issue at the dealership. Might be true as dealer has recently changed ownership.