Car travel (sitting too much/wrong way) has wreaked havoc for me with lower back/hip pain, and I haven't been able to run for some time now. Misery. It's worth getting checked out if it persists, since there are a lot of exercises that can help. Feel better soon, we all like to cheer you on flying past us in the woods!
Yeah if this doesn't help and it keeps getting worse, then I think I'll get it checked out.
The other thing to check is that you have a strong enough core, and that you're strengthening it without arching your lower back. Crunches are good, and anything else that engages your deep transverse abdominals. Good luck.