Changing routing on DBCFree ticket?
I used a DBCFree voucher to book a ticket to Las Vegas for later this month. I got a call from United a bit ago -- my layover in Dulles has been cut from an hour to 50 minutes. I was uneasy about the hour layover to begin with -- especially because the next flight isn't until 5 hours later -- so although I know 10 minutes is not objectively that much, it just makes me even more nervous. However, United is now showing a routing through Denver that didn't exist when I booked my ticket -- I guess maybe as the result of other schedule changes -- that would have a 90 minute layover and get me into Las Vegas only 30 minutes later than I was originally supposed to arrive.
Do DBCFree tickets work kind of like award tickets in that you can change flights as long as you keep your origin/destination the same? Or would they try to hit me with a change fee (I'm thinking that a 10 minute schedule change is not on its own significant enough to get a reroute -- am I right?)?