I dont think its a silly question, in fact probably a bloody good one!. Having roasted a few batches you really notice the drop in bean freshness after one week and after two weeks they are just about done. Now thats for a bunch of beans that arent vac packed, just sealed in a zip lock and stored in a airtight container. Id really like to know what defines the usedbyness of those beans, especially as it is two months down the track. When I bought some beans from the aroma fest earlier this year I noticed they were stamped with a roast date.
Dont be hesitant to ask cause you might sound like a snob. I mean thats why we are all here right? ;)