Cramps before positive OPK?

Hubby and I were out to dinner yesterday and I had sharp shooting pains that lasted most of the evening. By the morning they were gone. Yesterday at 3:30pm I had a negative opk it was close to positive but not quite. Today at 4:00pm I had a very positive opk. I have not had any pain today, is it possible I O'd yesterday even though the surge didn't occur till today? We BD'd last night and will tonight as well.