You should because radon is the leading cause of lung cancer among non-smokers. As a tasteless, odorless, colorless gas, there are no physical warning signs of the presence of radon. Testing is the only way to find out.
While radon isn't a certainty in Michigan, there are definitely pockets in the most unlikely places. I've been surprised by high levels (over the 4.0 pCl recommended by the EPA) of radon in some of the homes that have been tested. In one case, it spiked to 70 during a one hour period!
I always recommend my buyers have a radon test done during their inspection period. If radon is found in the home, then the remediation and repair is on the seller's dime and the buyers have peace of mind that it's no longer an issue.
If buyers choose not to test, they not only may be jeopardizing their health but if elevated radon levels are found when they sell the home, they'll be on the hook for remediation.
Better safe than sorry.