Immersion switch tripped mini circuit breaker for two weeks but presently seem fine.? My immersio water heater seem to be tripping my mini circuit...

My immersio water heater seem to be tripping my mini circuit breaker when it automatically went on in the morning for more or less two weeks. I hadn't gotten around yet to tracking down electrician/ plumber to look at it. It seems to be fine in a minute for last 3 days. Any idea why it happen and why its corrected itself now?
Flea infestation?
Answers:    IT MAY BE THE HEATER,BUT IT COULD BE THE THERMOSTAT.THE THERMOSTAT IS WIRED INBETWEEN THE HEATER ELEMENTS,TURNING THE HEATER ON AND OFF.NOW IT HAS STOPPED TRIPPING,HOW HOT DOES YOUR HOT WATER CYLINDER GET,IS IT GETTING EXTREMELY HOT?
Home construction/repair grill?
Get it checked out soon , the heater could be breaking down which could be the motive of the circuit breaker tripping , which is the first signs of your heater is on the way out .
This may be a silly cross-examine, but does...
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answer mine please.