I agree it should be covered especially if you just had the frame replaced.
The short rail was a manufacturing defect, one that they recognized and decided they would fix. The right thing to do.
I'd call again and make sure they understand you just got a new frame and be clear. If all else fails I'd have your local dealer ship it for you since they can ship it cheaper than an individual.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."