Migration Assistant failing on Time Machine: "Backup in use - try again later"

I am setting up my brand new MacBook Air, and an unable to restore from my Time Machine backup. I made sure my backup (from my old MacBook) was complete last night before I erased the hard drive (and then traded it in). Any thoughts on how I can get this data? (Worst case, I have it on the Cloud, but that will be a MUCH slower restore)