No; she's untanned where her school swimsuit covers her. Her midriff shouldn't be tanned. Nanashi must've forgotten that for a bit, but he apparently remembered during the shower scene, which he evidently spent more time on.
And someone else pointed out that the artwork was (in general) a bit more sloppy, and the mistake with the tanning is just another example. I get the feeling that Nanashi is trying to knock some of these out in a hella hurry.
That manga has been a pathetic lost cause for a LONG time. I ditched it 10 chapters in due to not only the premise being absolutely stupid, but the male lead being a total worthless POS with no spine and with a pathetic masturbation habit.