The short answer is yes. Zoning standards change all the time and for a number of different reasons. A change may mean that your home does not conform, but it does not mean that your home is in violation of the new zoning codes.
Think about the movie "Up" -- or just think about most neighborhoods in South Minneapolis. In the movie, Carl and Ellie's home starts out in a lovely residential neighborhood; over time, though, the neighborhood changes until the house is surrounded by skyscrapers. The house may not conform to the current zoning code, but it did when it was built.
The same is true in Minneapolis. One block may be apartment building after apartment building, with one lone single-family house tucked in there. Or, on the outskirts of downtown, there are beautiful old mansions alongside apartment buildings and one-story commercial developments. Something in there has been grandfathered in; it's not illegal, it's a legal nonconformity.
When zoning changes come up with local governments, owners of existing structures in the affected area can look to Minnesota state law for protection. The structure will be classified as legally nonconforming even through restoration, improvements, maintenance and repair, even replacement, under one condition: If a structure is destroyed to the extent that it loses more than half of its market value, the owner has 180 days to obtain a permit to rebuild before the new code is enforceable. At that point, the home or commercial building will be illegally nonconforming, and that means trouble.
Another important point for landowners: Not conforming with zoning is not the same as violating building codes. To learn more about the state's health and safety codes, go to the Construction Codes and Licensing Department website home page or 2015 building code page. If you have questions about your own situation, contact CCLD or a real estate attorney for guidance.
Source: Minnesota Department of Natural Resources, "Nonconformities Factsheet"