What I've found before in other places online is that when doing a simple copy/paste from one page or site to another, it can copy formatting indicators, etc, possibly even other meta data, that you don't see on the surface but adds to the character count. At least that's what it seems like, when notices show up saying you're over. Copying from one page then pasting into something like notepad or simple text, then copying from there to paste into the desired destination strips it down to just your text. I've run into this numerous times on places like craigslist when copying a past post to a new one; pasting it first into notepad then copying from there to paste into the new post eliminates their popups saying disallowed, etc.