Is it possible to get a false positvie for HPV?

I tested positive for HPV 3 years ago. I was retested again within a month and it came up negative. At the time I was told someone in the labs messed up and it was a false positive. The year after that my pap results were normal. I was just told this year that I was positive for HPV. I've been sleeping with the same person, and only that person the whole time. Excluding the possibility I was cheated on, which I think is quite low, what are other possible explanations for this?