That was the first thing I noticed as well - out of focus shots. As an astrophotographer and fellow lightning photographer, I've had lots of practice getting the focus right at night as well as ending up with lots of fuzzy shots.... First, I try to use a lens that has the focus indications on it (my favorite night-time lens is a Sigma 24mm f/1.8 which has infinity clearly marked). I'll look around to see if there is something bright enough to focus on (like the Moon or city lights) that are at infinity. Alternatively, I'll focus in the daytime and check and see where infinity focuses on the lens and carefully set the lens focus there at night (also, always rotating the focus from the same direction to avoid backlash issues). Shooting stopped down a little (to f/5.6 or so) also helps with the focus a little.
As you've probably learned, night-time lightning shots are not all that hard to come by - using a long enough exposure and pointing at the center of a distant lightning storm makes the task quite easy. The hard part is adjusting the f-stop and ISO speed of your digital camera to get a well exposed bolt. Then the length of the exposure controls the number of bolts and the exposure of the scenery.
One other thing - try to get the horizon straight. And practice, practice practice - you'll get lots of cool lightning shots!
Jim.