someone on FB liked my tumblr activity but notification on FB links to "page not found" ?

[MoonCloud]

I was on tumblr tumblring on as usual, and i wanted to share a gif on facebook, but as most of you know, gifs are not yet supported on there so I figured instead of copying the img link, i'll press this like button below, that the tumblr user had put there. i go onto facebook to see what happened, and I can see nothing, so I dont think about it anymore. then a few hours later, someone likes my tumblr activity. it should be mentioned that i do not have my tumblr connected to facebook in any other way. so i get curious to see if there is a post and how it looks like. so I click on the facebook notification but the link turns out to be a "page not found". if my friends can see this activity, why can't I? and what is really wrong here, is this a fault by tumblr or facebook?