Clear Blue advanced digital OPK

Has anyone ever gotten a false positive? I took the test one night after holding my bladder for 12 hrs (worked and had little fluid intake) and got a empty circle meaning not near ovulation. I let a day go by and tested the following morning. So about 36-40hrs later, with first morning urine. And got peak day. Solid smiley. Not sure if it is false or if it could even give a false positive.