In my experience, 4 weeks for primary before lagering is way too much because I do a diacetyl rest.
Your beer will benefit from a long lager period of at least 4 weeks but if you are doing a diacetyl rest, you want to move the fermenter from primary to room temperature when airlock activity is very low but not completely ceased (no fermentation). One bubble per minute seems to work for me and that generally comes after 10-14 days after pitching.
If you transfer the fermenter to room temperature when fermentation has completely ceased, the diacetyl rest will likely not take place properly and that may result on undesirable tastes, especially in light or less complex lagers like Pilsners.
Now, if you are skipping the diacetyl rest by progressively reducing the primary fermentation temperature, then waiting 4 weeks on primary may not give your beer any problems; however, it is known that some lagers benefit from some degree of residual sugar fermentation during the lagering process (SG should be less than ¼ of the OG).