Very hard to know without actually seeing it in person. It could be a paint defect/ie a bad patch job, or could be malicious damage. The 350 bonnet being aluminium is very soft, so if it's hit with any impact it will leave a dent, if lightly maybe not. The beginning point looks a bit deeper than the far end.
I went through similar when my bonnet was hit by a large bit of flying metal, it left two gouges, 2mm deep and a dent. With the stock paint it is very thin, so to my eye, your pics don't depict stock paint, ie patch job. I could be wrong.
I was lucky, as I wasn't prepared to have imperfect bonnet, so managed to source one from a dealer at a very good price, had it sprayed, gloss on the the underside too.
If possible can you take some better pics???