Mild cramping can occur for any number of reasons: cysts, ovulation, hormone change, gas, constipation, viruses or bacteria. Just about any reason. I had mild cramping the week before I was to start my period, along with all my other normal premenstral symptoms. Only my period never came and I am now due april 23rd. The cramping continued for about 3 weeks, and has now mostly subsided. I am a little over 8 wks into my pregnancy now.
Hopefully for you it is just your body getting ready for the ovulation. If you just finished your period and are trying to conceive then I would suggest having sex every day from now until 2 - 3 weeks from now. When finished with the act linger in bed laying on your back or side. Some suggest even putting a pillow under your rear to help keep the fluids in. Good luck and keep us posted!