The seller failed to make a material disclosure to you concerning either a defect or litigation which may affect the value or integrity of the house. You have an actionable matter that it sounds like you would rather not pursue. It could be that your drivit is in good condition and will never cause you any problem. That seems consistent with your inspector's findings. On the other hand, the seller may have had some knowlege of defects not disclosed to you, or may have entered the Drivit lawsuit simply because he qualified to be in the class.
You should confront the seller directly or though an attorney to determine what reason they had to participate in the class action suit. Provided there are no apparent defects there is no reason to pursue the matter further. The seller left himself vulnerable in this matter, but it may not amount to a hill of beans provided everything is in working order. If however a defect is present you now have recourse to be compensated for any damages that failure to disclose may have brought.