If I were you I would run

If I were you I would run a couple of tests before attempting to shoot anything of value. I have seen this same sort of issue before only much worse than you described. In the tapes I looked at the first minute or so was all jumbled up like you described, and there were glitches throughout the entire tape every 2 seconds or so. This occured tape after tape after tape. They had to replace the entire tape mechanism on the camera. It started out as a lesser problem, but continuously got worse. I would have it checked out by sony techs if it occurs again. As the previous post suggested, could be condensation, but could be a developing problem as well.

Later
~Adam