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It may be that there is nothing actually wrong but that is just too much load for a hot day on that new an engine. Keep it down and get some miles on this before you push it that hard. Any hills will make this worse. Be sure you are using the correct oil and filters and pay strict attention to the servicing schedule. I don't blame you for being cautious. Hope that helps here. Please get back to me if you need more on this as all follow ups are included in our fee.
Could be, but usually you would see more issues like this at lower speeds if that was acting up. It would be a good idea to have it checked when you can get into a Service Center.