most bad back are because you dont exercise your core muscles enough
your core supports your back,and dead lifts are no good for core 
your talking b*****x mate...sorry....i know loads of fitness guys that have trouble with their backs at times(and some of them are really shredded!)....its just the way it is....no matter what you do in the gym....
anyway i feel fine tonight....its ok now just a back strain from lifting 2 sofas down stairs on sunday! 
its your posterior chain than needs strengthening(hamstrings,glutes,lower back muscles as well as core).........to help your back but still its a strange one the lower back sometimes......anything can set it off....
sometimes im fine for 6 months then itll go and ill be in pain for a few days.sometimes its been bad for a month or so.....swings and roundabouts.....
thanks for that
think of it this way you strength all the muscules up the back of your back
but think of all the muscles up the front of your body,if the strengthen isn,t equal in front and back of the body this can cause back pain.
dead lift are a classic for causing tight hamstrings if not done right, has must people pull with the upper body and not from the hips ,which if not done right can effect the back,