Looks like I had the same/similar problem. I did a coolant flush and there was some "crud". I guess it was left over in the block, or the heater core since the radiator was fairly new. Anyway, made sure to get all of the air out this time and all seems well. Drove about 60 miles, nothing pushing out. Of course it was only in the 80's yesterday, and not 105 like the last time, but still...
Now on to the next problem..
Thanks guys!!