The last step in transferring the domains from sibername.com to canreg.com was to obtain an "auth code" for each of those domains and send them to canreg which they'd then include in the transfer request to sibername (presumably the auth code somehow shows that the request is coming from the actual owner of the account).

Canreg.com put in the transfer request and was told by sibername the the "transfer lock" on each domain had to be removed by the owner of the account. So, I logged in again to the sibername admin interface, clicked on manage domain name, clicked on the domain and then found a un/lock button at the top of the window (beside the auth code button I used in the last step). Unlocked each of the domains. Sibername guys might have included that detail.