I think this is something that Supplier's need to make sure is on their liquids! I rarely see a date on what I purchase. I do keep records printed off so I can identify where I got flavors at and when they were purchased. I probably should just use a Sharpie and write the date/supplier on the bottom of the bottles.
I'd think if you are ordering from anyone on this forum, you can be sure that it is pretty fresh. They don't seem to bring in that much, and run out of stock frequently enough (especially lately since people are stocking up).