age is not as much an issue as how it's been stored- i've bought expensive (new) thread- from shows/lqs that wound up being (garbage) and i've used thread from my grandmother's sewing box (probably 30-40 years old) that was fine.
if it's been in storage for a long time it may not be a good thread...it's hard to tell without doing a 'tug test' on it to see how easily it breaks- can you ask...how it's been stored-where it's been?