It means that the timeout period expired (probably 5 days) before
stjohns was able to contact usa1.com to deliver the message.  This
indicates a major network problem somewhere....in essence, there is
no route from stjohns to usa1.
 
On the other hand, the severity of the problem really depends on
how long the timeout is at stjohns....if it's 5 days, it's serious,
if it's 4 hours, well, clearly it's not really a network problem.
(I hasten to add that I imagine that stjohns is configured properly,
and am adding the above to cover "general" cases.)
 
Nathan