George,
Almost looks too crisp to take on the wild trails of Colorado.

Very nice. Congratulations.
Burping a bit of coolant may be that you just over-filled it a bit. I've had this happen to me also...but only after I refilled, or replaced the coolant. Then it doesn't do it again.
I looked back at your fuel lines in past photos. You look like you did a good job of keeping them away from the manifolds. 100� is even hard on a modern vehicle, so I don't know that I would be too concerned just yet. The float could need a slight adjustment, or something else minor. I once had an issue with my filter. I didn't tighten the screw enough. The screw that pinches the glass against the top. I was drawing in some air and had a stumble.
Were you at a stop during the stumble...or on the throttle?