Firstly you have nothing to do for such mistakes. Although there is no such notification regarding the discrepancy of thumb impression and what are the necessary steps that will be taken by NTA, but from a common sense point of view, I don't think the finger imprint will be matched with your digital print of your aadhar. As from some of the articles of fingerprint sensing, such cases can cause discrepancies and variation. So you have nothing to worry about this, I don't think it will create a problem although there is no official grounds of saying so. But its just my guess based on the facts available online.

I hope this answer helps. All the very best for your future endeavors!