I'm not sure how far out your trip is, but keep an eye on it to make sure they don't make drastic changes. The good thing is if they do (I *THINK* it's one hour difference in arrival or departure time), you can call and have them change you to any flight that day for no charge. We've done it often when travelling with family, book months (think 6+) out on the "cheaper" time, Delta makes a "significant" change, so I have them move us to a better flight (that was MUCH more expensive).
And by "keeping an eye out", I just mean checking every week or two. They will try to notify you, but don't count on it.