Yes the 30 amp will literally turn off by it self ..as if some one pushed the test button.. My spa has never done this Ive had it new since 2003. Something must be over loading it. I just dont know what yet.
When you say the breaker trips, is the breaker switch literally turning to the off position BY ITSELF? I'm sorry if this seems like as stupid question, but it's a very common mistake. If the breaker is actually turning itself off, then yes indeed it's tripping. This would indicate either an electrical problem or a bad GFCI breaker.
If the breaker is NOT turning off, and you're just having to turn it on/off to get the spa working again, then there's an issue with the spa (and in that case the breaker is NOT tripping off).
Most commonly, if the spa itself 'trips off' randomly, or over a few days, it's probably a poor flow issue due to older or dirty filters. If you have not done so already, remove the filter from the spa entirely and see if the problem still occurs. It could also be a flow switch issue if the filter doesn't correct the issue.
Edit: Generally speaking, the breaker itself will only switch off if: 1) There's an electrical problem (Ground Fault, short circuit, too much amp draw, etc) 2) The breaker is failing.