CF Card failure - a bit different

I have been using sandisk cf cards for over 8 years with no problems until now.  When I tried to download a 64gb extreme pro it stopped after awhile and gave an error saying it could not conect to the external device, I was able to complete the download with a cf card reader, I reformated the card in the camera and it seems to work, though I don’t quite trust it, it would be disapoinitng to loose images that may not be easy to recreate. The price of cf cards has come down quite a bit but still pricey.

The card was about .25 full, I have filled 64gb to within 5 to 50 images many times without a problem.

I am wondering if there were some corrupted bits in the card and by reformating they are now excluded from the usable memory but not sure about that.  Any thoughts on wheather to keep ot toss the card.