There has never been temporary SSNs. You had temporary work status, but your SSN is valid (and yours) forever.
You might want to go to a local SSA office when you are in the US to get a new
card -- or do a mail-in -- as employers are a bit leery to take a foreigner's word on SSN these days.
http://www.socialsecurity.gov/online/ss-5.htmlOne point though is that, because you are not a citizen and because there is so much fraud in this regard, they will not replace your card until you actually have your work status, so its a good thing you still remember the number; that will get you through the first while.