Mash Temperature Inversion

Hello, I'm just wondering if anyone else has noticed a large temperature inversion in the mash. I have a temperature probe that comes in from the top of my mash vessel (a large stainless pot), and I can move it around. I'm brewing right now and the temperature at the bottom of the mash is ~160, and at the top it is ~152 F.

If I stir it up the temperature at the bottom approaches my target temperature, but right away it starts climbing back up.

Should I just relax, have a home brew, and not worry about it?

Make sure everything is well stirred and check in about 5 mins. If the temp hasn't stabilized might consider a little cold water to bring it down to target.

I guess what I really want to know is if an 8 degree F temperature differential between the top and bottom of the mash is common.

Are you heating your mash tun while mashing?

I have heating pads on the outside that kick automatically in when the temperature falls too low. The temperature difference happens right away before the hearing pads turn on.

Is your manifold copper and if so is the end of probe touching it or very nearly so? Copper holds original temp. longer. just thinken. Cheers

Thanks for the suggestion. My probe is ~1" above the bottom when it is in place. The bottom of the pot does have some layers of other metals that could hold a bunch of heat from when the hot water pours in. That could very well be the reason. Good idea.