I've got pork ribs in the crockpot and after 4 hours I noticed the lid was slighly askew - not much, but not completely seated. I'm going to cook it a little longer, but is it safe?
It is not a pressure cooker. It will still get hot. The risk with the crooked lid is that it will lose cooking fluid to the air. If it is like that overnight it might cook dry and that would be bad.
If it looks to you now like the fluid is low, add a little more beer. If you did not add beer in the first place, now is a good time to start.