You couldn't use a USB key instead?
Don't underestimate how vulnerable you are when your email gets hacked - virtually every service you use can be accessed by the forgotten password mechanism when your email is breached. I'm pretty lazy and have procrastinated for a long time, but with the recent attacks and realizing what a mess I could face if hacked I finally implemented two factor auth and I have no regrets yet.
To access files in this situation, a better approach would have been to upload the file to a webserver. You can then safely download it from the library computer without anything being compromised.