Can you please give me your best advice and opinion on how to deal with a issue I have at my 20 year restaurant job?

I have been an employee (an opening cook at a major restaurant chain) for 21 years and counting. I have been in this role there for about 16 of those 21 years. Over those years we have been near the top in sales and food cost, labor etc. some of the time. I have been in the same role even when a former manger won manager of the year in the district for having best numbers. However right now we have missed food cost (not by a whole lot ) the last 5 months or so. The district manager has brought in an experienced manger from another store temperolariy to show one of our managers what she needs to learn to help the restaurant make food cost. He is going after food quality etc. throwing many things away. I myself am very patient with the less expereniced cooks. (most have been there less then a year. All the mangers who have been there show respect towards me and usually have me fill out my production chart, make calls on things etc. some of them can be loud and mean to some of the other cooks .

I feel this transfer manger has been going at me he uses a different tone to talk to me sometimes. He works at another store in the district who at the time is making there numbers but has not always been the case. All m co -workers and new hires that I train say things like I was the best trainer I ever had in a restaurant.

To finalize this, I think I am trying to ask you how I can not let this guy make me feel less about myself. How do I not let it bother me?