I was wondering what would cause this problem so I can address it in future shoots.

I noticed in two pieces of footage a slight problem. In one shot I noticed in post that the edge of the persons white collar kind of sparkled, like either the camera was going in and out of focus or artifacting. In another shot, behind the person was a dark colored board with small numbers on it (like a chart). Some of the numbers did the same thing.

I was shooting in manual mode, with manual focus and adjusted for what I would have thought was good exposure. What may cause this?

I was able to fix it in PP2.0 using the flicker remover.