Flight Log Not Complete

After my glider flight today I downloaded my flight log from the LX9050 to an SD card as usual. When uploading for an OLC claim I get the message "A clock jump was found in the recording. The flight was shortened from there". Only the last 7 minutes of the flight is indicated. It was a 3 hour flight and the file size is the about the same for my other flights of similar duration. I won't know if this is a one time thing or if there is a bigger problem until I fly again. Has anyone else had this happen?