M.J.
Yes. I'm in the 1% who had a false reading on a HPT and it was a positive. In fact, it was on a digital pregnancy test that read "Positive," so there was no chance I misread. I only learned the truth when I went to the ER with what I thought was a miscarriage only to embarrassingly learn it was my period. The doctor there said, "Well, someone has to be in that 1 percent." Ugh, it was me.
It's rare, but it happens. You did the right thing to get a blood test. I don't trust HPTs at all now.