I would be heartbroken, yes, but only because I have gone thro several years of tears from my 12yo DD2 about her dyslexia now, and it kind of hits a nerve, especially as both her brothers are also now flagged as being dyslexic and are finally getting the appropriate support. Not before time I have to say, but all a bit late for DD2 and DS1 as they are very sensitive about it now and it therefore has had an effect on us all.
and.......it can lead to bullying, which is even worse.
It is human nature, I get that.....and I can see (a little), why you would do it, but the problem then comes if you mention it to your child, who then goes into school and mentions it to another child, and then, like chinese whispers it goes around the class and before you know it my child is being teased because some mum made a comment. children can be very cruel, this I know, and that is why, yes, I would be heartbroken.
I am not in any way suggesting that any of you here would do that, (the commenting to your own child), but it can happen, and does.