When you have millions of pixels on a video sensor it isn’t surprising to find that every now and then one or two might go out of spec and show up in your footage as a white dot. These “hot” pixels are most commonly seen when using high ISO’s or the upper of the cameras two base ISO’s. Hot pixels are not uncommon and they are not something to worry about.
Thankfully the issue is easily resolved by going to the cameras main menu and – Setup Menu – Setup Option – Pixel Mapping. Then cap the lens or cap the camera body and run the pixel mapping. It only takes around 30 seconds and it should eliminate any white, black or coloured sensor pixel issues. The camera will ask you to do this periodically anyway and you should do it regularly, especially after flying anywhere with the camera.
Sensor pixels can be damaged by energetic particles that come from cosmic events. So a hot pixel can appear at any time and without warning. They are not something to worry about, it is normal to get some bad pixels from time to time over the life of a camera. When you travel by air there is less of the atmosphere to protect your camera from these particles, so there is a higher than normal likelihood of one going out of spec. Polar air routes are the worst as the earths magnetic field tends to funnel these particles towards the north and south poles. So, whenever you fly with your camera it is a good idea to run Pixel Mapping (or APR if you have an FX6, FX9 etc) before you start shooting.