Temp differential between Mash probe and recirc probe

I recently did a huge upgrade and now have a single tier system with 15 gallon pots, pumps, copper mash manifold that drizzles on top of the mash etc. etc..

I have a BCS 460 with 4 temp probes. I have one in the port at about the 6 gallon mark on each pot and in the MLT, I have an extra stainless tee after the ball valve on the bottom to measure liquid temperature as it enters the pump. I am driving the burner using the probe that sticks into the grain so when it goes below setpoint by a few degrees, the burner turns on and stays there until it gets back to setpoint. I have done two batches now and towards the end of a 60 minutes mash, the burner will kick on and the recirc probe will read in the 170s while the mash probe is in the high 140s trying to get back to 149 or 150. I try stiring the mash and it helps but at the end of the mash cycle, I really want to leave it alone so I can get clear wort.

Should I drive the burner from the probe in the mash or the probe in the wort? Should I worry if the wort temp gets that high (tannin extraction etc) or does it now matter as long as the grain is at the target temperature?

Just trying to understand, you're direct firing the MLT and recirculating bottom to top?
I think I'd try to control the temp of the wort rather than the mash temp itself. At the end of the mash it's not all that important, but if you were to run into this scenario in the beginning you'd denature the enzymes by overheating the wort trying to alter the mash temp.

Yeah I guess I didn't explain very well. - I have a direct fire rims system. The recirc probe measures wort temperature as it leaves the mlt, the mash temp probe sits in the middle or so of the mash (grain and water).

After thinking about this some more and realizing that I have no experience with a RIMS system - I should probably open up the pump valve more so that it recirculates the wort faster. As I get to the end of the mash, I can close the valve a bit to create a nice filter bed for sparging (I am fly sparging).

I believe most RIMS systems are using the output temp of the RIMS vessel to control temp, for the same reason as I stated - you don't want to overheat the mash liquor when trying to perform a step (or maintain temps).