I have a 510, an older model.
Mine isn't as indented as that, but there is a slight deformation.
I suspect it happens when the two layers of plastic are compressed as the bailer is fitted.
It still works fine and I don't think it perceptibly affects boat speed.
If you are concerned about small fractions of a knot affects on boat speed, you are paddling the wrong boat! 510s aren't quick boats.
They are reliable, durable boats that are a good introduction to surfskis (or, for someone who also paddles in touring mode like me, a terrific all-round boat)