I'd complain to the lab it's probably caused by their processing machinery. Poor maintenance is usually the problem.
Yep, I'd definitely ask the lab for a redo.
One wild card here is the quality level of scan that you paid for, not all lab scans are created equal. If you only paid enough to get the basic "big enough" for email or web use scan that would explain the issue too.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Ana´s Nin