I have an early April trip where my connection time in ATL was changed from 1:45 to 0:39. When I called DL to try and change it, I was told that's a legal connection in ATL (they are selling it that way on the website but I certainly wouldn't willingly book it!) and if I wanted to change I'd have to pay change fees and a significant fare increase. I hung up, called back a couple of days later and got the same answer. I presume that being that far out, it'll change again, and by the time it does I'll at least be FO and might be able to get something more favorable.
Check out
this thread. Try using email or Twitter. I would not have a big problem with a 39 minute connection at 9 am but that would be unacceptable in the evening.