Now this has not yet happened to any of my memes (matter of time I expect), but when I browser around on imgflip I see it more and more. Some "complaints" are even given on memes where the poster already noted it themselves it was a repost, which makes it even more annoying. Some memes being targeted actually do appear to be original (at least I used the posts in google image search and the only hit I got directed to the imgflip page, and that is all I can do to check).
If this were a site where we were posting big serious projects, like a game you coded yourself, or where you present music to build up a portfolio, I could understand, but a meme site... a place where we simply post stuff for fun... that goes a bit far.