I've heard of people that have just tightened them out of sequence and nothing catastrophic happened, then there are others that bent valves. remove the rockers, check your push rods. if you have a bent one I can promise the valve is probably in the same shape. if they all look good re-install all everything in the proper sequence and fire it up again. If all is well you will be good. If you still have valve noise be ready to pull the head(s)