I'd do some reading. I'm a bit dubious about the affair at the moment: I mean, you go to buy a house, they do a radon test, it reads high because it was raining. Suddenly the seller has to put in a radon mitigation system. But oh wait, if you install now, it's 10% off and only a grand (or whatever) to put in. Ok nothing smells wrong here. [That's what the seller of my current house went through.]
I spent a little time reading on it, and haven't gotten around to looping back on the subject (moving is stressful by itself). IIRC more than a few resources were doubtful about the short term test that is typically used, and a few mentioned that the reading is impacted by the weather. What was best was a month long test.
YMMV. The seller had mine put in and that's that. Maybe this summer I'll get around to retesting.