News outlets keep repeating "11 pages of 4-point type totaling 2560 characters", which just doesn't match up since that number of characters fits on one page in a fairly normal font size. Also, RSA keys just aren't that big, so the 11 pages must have either been many keys or some other data.

As I understand Lavabit's architecture, there is no "master" key. Instead, incoming mail is encrypted using an asymmetric per-user key. All the key pairs were created by Lavabit and stored on-site, but locked by a password to be provided over TLS. Since Levison probably didn't compromise his system to store users' passwords, presumably the keys that he was handing over in 4-point type were still locked with a password.