Mine came with macOS 14.1.Has yours macOS 13.5? My M3 (not pro) 16GB 1TB has macOS 13.5 installed on 26th August. Bit of a surprise!!
Not yet offered to upgrade of 14.x.
Another interesting thing happened when I wen tot pick it up... the apple store staff couldn't 'receipt' the device. They scanned it an it was showing as not in stock even though it was in their hands. They let me take it and said they would sort it out later. Just now, 3 hours later the tax invoice finally landed in my email and the device shows as picked up on the appstore app. For the last 3 hours it still was 'ready for pickup.'