I sent my M9 in for minor service - rangefinder vertical alignment - over 3 weeks ago. Anticipated final return is another week.
Seems to me that 4 weeks for service is a bit out of line. Or maybe the M9 is unreliable and often needs service. Or maybe the service department is short staffed.
Gone are the good old days when Leicas were actually manufactured in Canada and service was almost "instant".