Found this little gem out earlier this week. Was on a SEA-DTW-MEM-FLL-IAH-MSO-SEA run (all within 24:22). Tried web checkin which returned an error. Called nwa.com who told me it's due to having more than 3 segments within a certain period). Tried checking in at the intermediate stops, no go either.

Tried e-checkin at SEA. Same problem (screen said to see an agent). Told the agent who was disbelieving (she said she never saw that one before) but saw it with her own eyes.