Facebook likes disappear after amending a blog

I may have realised a problem and this may be a bug. If I publish a blog and it gets a load of likes for example say 10. If I then notice a spelling error in the blog and I go back into it and correct that mistake and save the blog the likes disappear (as if it's a new blog.) Surely the previous likes should still be there? This is also happening to the other social integrations ie Twitter, Google+.