I had an interesting phone call yesterday when I tried to change an AS award ticket from PDX-MSP (DL) to FAT-SLC-MSP (DL). Before I called, I verified on AS.com that saver coach seats were available for the new DL flights and when I talked to the agent, he was genuinely perplexed because he could see the flights showing as available on the AS website, but they weren't bookable on his computer. He ended up putting me on hold for awhile so another agent could help him determine how to book this. He eventually came back on and said that DL award flights to MSP were blocked out for weeks. He could get me FAT-SLC, but not SLC-MSP (even tried SNA-PDX-MSP but the PDX-MSP DL flights that showed "available" online were not bookable). Definitely an odd situation I've never run across...at first I thought it might be some sort of beginning of the end as far as the AS/DL relationship goes, but he said this was specific for DL MSP bound flights and he didn't know why.