Maybe it was a glitch, or maybe you didn't finish the save process. IDK, but if they deleted it the first time for rulz, why didn't they delete it again the second time and then warn you?
-PJ
The image was there yesterday because I always check and I linked to it in a post and it showed up then.
I have never been warned, but I have had one removed before, a gif of a jet turning its chemtrail on and off.
I do not believe they bother warning you.