LH short surge or false positive

Hi, just wondering if this is normal.. Tuesday about 9pm I had a negative opk but it was quite dark, Wednesday 8.30am I had a positive opk, darker than control line, then 12 noon, 6pm & 10pm all negative! Was this a false positive or a very quick surge? According to glow I was due to ovulate on the Wednesday but just seems so quick?!