Real OEM part numbers usually are correct and give the full on in date use of the part for a car. So chances are that if a car was a month back it is a 50/50 shot if the parts are of the new revised edition or the older stock. That being said Not every car is affected but there were issues found on cars that had long service intervals. Like the BMW 12K miles oil change (Total BS, change your oil every 5K) But better safe than sorry as it is a expensive repair but I think BMW has a extended service interval on this issues.
The numbers they mention are of the production of car for that start date. So 1/2015 means any cars built during that month and onward have the latest revised part.
You will never get the correct answer to this question but easiest thing to check would be to look inside your oil cap. If you have a really dark brown/ caramel chain guide than you have the older chain. If it is a coffee color chain guard than it is the new chain as the new plastic pieces that came in the kit are white and will get a little darker with oil and time. And BMW only replaced the entire assembly not just the chain itself as it was both the chain and the guides that had issues.
OLD Chain Guide:
New Chain Guide:
