I agree with Eric as far as it being an exertional type headache. We have quite a few threads on the boards about them and basically slowing down and watching your breathing usually helps prevent them.

Taking a step back in the meantime for a week or two until they go away completely is also a good idea. You don't have to stop lifting, but maybe just decrease the load. If you feel any sign of them coming on during the lift I would stop as you will just be setting yourself up for some pain.

I have personally had them during heavy deads and can tell you that they aren't fun, especially when it feels like someone punched you in the back of the head. Also if I still went at it full force during my next session they would have a much higher tendency to pop up as compared to stepping back for a week or two.