My question to you is, should I be worrying about this, or should I just accept that 58 kg is about where I should be? Particular weight, haha, will be given to the opinions of those who have seen me in person recently.
Should I start dieting to lose that last 3 kilos?
Yes, you have a goal, stick to it, you'll feel good when you get there.
No, you look fine the way you are. Don't worry about it.
Auxiliary question: Complaining about one's weight: is it socially acceptable?
Skinny people should not be allowed to complain about their weight. Eat a hamburger and shut up.
Fat people should not be allowed to complain about their weight. Get on the treadmill and shut up.
There is such a thing as an average weight that is both healthy and attractive. Really! Most of us are there! So shut up!
There are people in the world who think Angelina Jolie is a heifer. BRAIN SPLODY. SHADDAP.
I don't want to think about this. Ticky box, please.