I read this forum on my phone so occasionally, as I'm scrolling down the page, I accidentally touch the 'dislike' button on a comment. I don't have the option to 'undislike' after I touch it. Once I touch the button, I can't change it. I don't know if it works differently on other browsers but that's how it works on this phone.
So if your comment received a 'dislike' don't feel bad. It may have just been me by mistake.
Sorry about that.