In the Midwest, if you don't like the weather, wait five minutes and it'll change. If you're in Kansas, Oklahoma or Nebraska, you'd better like the wind because it's a constant factor. Temperatures are slow to change along our coast, or at least they're predictable. The West is noted for gorgeous sunsets. In the Midwest, it just gets dark.
Beautiful sunsets are rare.
Folks in the Midwest are polite. There are a number of ways to handle this sort of gesture. But sometimes you get caught off-guard, so you have to do whatever you can to return the greeting. It's a little thing, but mighty important to Midwest folks. We Southern California folks certainly can be friendly, once we know for certain the other fellow isn't going to take our wallet, try to sell us some land in Arizona, or ask us to serve on a committee.