So I did a bit of trouble shooting. The SM045 has a 750w heating element. In my outdoor patio outlet the GFCI trips after exactly 6 minutes, so it is a timing issue, long term. I plugged it into a different GFCI via an extension cord and it worked just fine, no tripping. The same GFCI that is tripping is where my wife also plugs in her 2,000w hair dryer and she can run that beast for over an hour, no tripping. I suspect I have a bad wiring out to my patio as this makes no sense to me. I have an electrician coming over and will ask he investigate. A neighbor of mine said he had exactly the same problem, same wiring scheme with out door patio outlet connected to the master bath GFCI, same tripping on his Traeger. Electrician fixed it. Said all the house in my area were built by same builder and most likely all have similar issue.
I contacted CS and they at first suggested my element was leaking and may be bad, but after it worked just fine in another GFCI we concluded it was something to do with that circuit/outlet. Need an electrician to fix.