Probably nothing. I just thought it was neat and I've never seen it before. I'm sure you guys have though? Merry Christmas and Thanks!
Yep, a late die state. 1964 was a BIG year for nickel production. In fact I think 1964 dated nickels were still being struck in 1965. Production was ramped up in conjunction with the "silver to clad" change in the larger face value coins. Check production in your Red Book.
There used to be a "magic" trick in the late 60's to ask someone to take a nickel from their pocket and then you "predict" it would be a 1964, that's how common they were.
The fellow enthusiasts nailed this for you. Billions of 1964/1964D nickels produced into 1967. That nickel might be from a later production and perhaps only 54 years old (despite the date on the coin). Because there are so, so many, they are often overlooked. But there are a number of DDO/DDR/RPM varieties for this date/mm, so do your research and look closer at your nickels...especially those in a higher grade. It is not uncommon to find AU/BU nickels in circulation. In fact, you can build an AU/BU roll for each mint in short order if you CRH much. Good luck!
Yes; at some point, those dies had to be getting pretty clapped-out. If you would like to acquire one that must be MS66+, i've got one available for a SASE. Get my email from moderators ( yes, please let Jeff C. have it) to secure my walkin'-around address. Thanks for starting an interesting post with a very mundane coin!