Being a genius is a good thing, and also not having “ego” motivations is looked upon favorably. So this is like an egoless brag.
Also: look at what I managed to do indirectly/without even trying.
I once got a top grade after passing an exam where I had read one page beyond what was required (can't remember if it was by accident, or because I was curious about something - but we're talking one page). After my presentation, the examiner asked a final question. This was covered in that page, so I just had to connect two dots and could give him a little proof immediately. Very little brain activity needed. Pretty sure I couldn't have come up with a proof on the spot otherwise.
I sometimes bring up that story as an example of why grading is stupid, but even though the point is how arbitrary the situation was, I can't shake off the feeling that people might think I'm bragging.
I think we should cut people some slack, if we don't know their intentions.