Thanks guys ill have a read of that link f1ex but there are lots of big words. Does look like that horizontal banding though. Thanks also, to the clowns
Just read through Flex's link and it certainly describes your issue, I might suggest that nothing is wrong, but certain conditions affected the way the data was being read from the sensor that particular time. Heat humidity all affect processor power/speed and it's all about that, if you concerned you could return it under warranty and get them to check it thoroughly, they may replace it!! Better to resolve it now while in warranty !
I know certain camera/video cams, actually refuse to work in high humidity "flashing warnings" and turning themselves off to self protect.
I'd definitely take the camera back.
If it is lines, or noise like artifact then it is the camera side that is the problem (e.g. sensor and imaging chain).
If it is a "light blurring" like artifact, then it is typically the AF, or lens side that is the problem.
After some reading it looks like it might be driver error, ill have to be less lazy/more patient. Pics I took the other night when not holding anyone up and with all tje time in the world came out ok. Now knowing it is horizontal banding so I actually have something solid to google helped a lot too! Must practice more