From my experince, when an element 'goes' it is common for either the main fuse or RCD (if you have one fitted) to trip. Normally, the element would then not work, or continue to trip your circuits (if still shorted). Your issue sounds a bit strange, but I agree with your thoughts and suspect the element has developed a shorting fault that only happens as it heats up.
JohnD
January 2006
I can answer this question...
how can i fix my creda electric oven from blowing main fuse?