It's just a page glitch - it occurs occasionally
Seems like these few days, admin started checking the outside links.
Like everyone else has said, there's a spamming filter which prevents users from posting links to unfamiliar sites (usually a filter is accompanied by an exceptions' list which includes domains like YouTube, Facebook etc.). This is to prevent spammers and spybots from spamming the main board.
It happened with me more than ten times. When it happens with you don't refresh the page, copy your text then change the url which you have included by eliminating the http or https part and removing "www". It works 99% of the times but if you get the notification yet again for a second time, replace the "." in the url with [dot]. This is going to fix the problem for sure.
Oh wow thank you ヾ(☆▽☆)
That makes sense, thanks. (=・ω・=)
Okay so i replied to someone's question on this and after i replied there was this message that read "This reply will be showed after approved!" in all red. Can someone explain to me why this happened when i only sent links... (⊙…⊙ )