Normal. Just the ends sewn together.
I’m not crazy picky, but I CAN tell you this, from the picture you have posted your bag is shiny and puffy and beautiful. If the slight crookedness bothers you, then you can always go look at other bags at the store and see what you think. The thing is sometimes the same flap looks crooked and other times it doesn’t.
Also, my beige jumbo’s interior isn’t taut, but my black jumbo is. My red jumbo is taut. It threw me off at first, but I’m the end, nobody sees it and it still functions the exact same when items are in it.
Totally up to you, but I love the puffiness and shininess of your jumbo!!
You said your bag was a 26-series? That seems a bit dated for a bag you just got from the store. Yours is a classic so there’s every possibility it was sitting in storage until now but it does seem a bit strange to me...