There's nothing wrong or suprising about having a sore lower back after doing a deadlift. Remember, it's a back excersize, and the lower back is almost always going to be the limiting factor with your deads because you will never be able to pull more weight than your back can propperly stabilize.
If you're concerned about your form and think it may not be as good as it should, I'd recommend going to youtube and pulling up some vids of strength coach Mark Rippetoe. He's done a whole slew of Crossfit demos that have tons of coaching and demonstration info on how do do the deadlift properly, and what it will look like.
Just type his name into the search bar and sort through the dozen or so vids that pop up to find the ones that pertain to the deadlift. The great thing about one of them is that he talks about how the deadlift will differ for people with diffrent body types. For example, the deadlift for someone with long legs and a short torso is going to look diffrent than it will for someone with short short legs and a long torso.
I ended up learning a lot from them. Dudes a genius.
Good luck bro!