I too had a really high index number 10. I got retested a week later at another lab and fell in the low positive range of 1.3. I got the western blot to confirm since it was weird how I could test so high then barely positive. I was positive on the western blot as well.
Not likely a false positive. That is a pretty high index number. False positives usually fall between 1.1 and 3.5. Though it isn’t totally outside the realm of possibility that it is false, since you haven’t had symptoms, you could get a Western Blot test, which is only done at the University of Washington. It can be ordered through them. If you want absolute confirmation, this would be the route to go.