A bit late with the explanation but yes, these things happen when the element gets hot and expands, which means it gets closer to the metal casing and as you discovered tripped the breaker, when it cools back down then it also shrinks back away from the metal, so in reality it could even be checked and not show the problem was the element.
But at least you have now solved the problem and learnt how to check the fuse board into the bargain.
My Turkish made electric samovar had a similar fault and when I checked the element the first thing that came to mind was that things like this just should never be allowed on the market, then again here in the UK they would not be.