Thank you kindly both, appreciate it. I wasn't aware that the SD card is formated that way.
And I've learned something new about the FAT.... thanks.
I format the SD card in the camera prior to shooting all the time, so why now only? I believe it's the same card...
I've filmed longer sequences before onto the same card resulting in files larger than 4GB..
But anyway, and as Olaf W. wrote "solution..?" I should maybe format the card through my computer (I'm on a Mac) and then use it in the camera. Then if it doesn't chop the file, I'll know.
But then I could try to format in the camera again and see what happens there.