Royal Oak Screw Heads

[SRQrws]

First, apologies for my lack of knowledge on this. I've been a Rolex owner for decades, but am looking to add an AP Royal Oak, steel, black face. My question is in regard to the screw heads. On the face side of the watch, the screw heads are carefully aligned to follow the shape of the case. On the model I'm looking at, the screw heads on the back are randomly aligned. Is this typical or is it indicative of the case having been opened? Thank you!