I've had that happen on my George Forman griddle ~ usually its only the first one, and because I use the "timed recommendation" but the griddle wasn't hot enough yet when I poured it. Glad they were edible!
Now I "test" it for release before I yank the griddle open (gently start to open, but peek in) ... if it starts to split, I let it cook for 1 more minute, and then it seems to release right (sticks to one side slightly, but comes off with a little tug)