Depending on your workplace and any related regulations or contracts that might or might not apply, this could be contrived to constitute a formal performance notice and a lead up to a firing where they will use it as evidence of a performance issue and your having been given due notice (for things like avoiding paying out related unemployment, vs, say, simply laying off a given employee).
It might not be about you, it might just be a routine thing managers are expected to send each of their staff regularly, but that's a risk that might not be worth taking: only you can really decide that, short of getting someone to answer about what triggered it being sent as addressed.
Personally, if it were me, I would:
(not simply "talk to" until after having sent something recorded, given the format of what was sent to you) the manager in question a reasonably formal, polite response saying (paraphrased) that you appreciate the reminder, you always strive to conduct yourself in that way, and if the notice is in response to any specific event where such conduct is believed to have occurred on your part, you would appreciate being made aware because you are, yourself, unaware of anything related having happened, you would hope that they would of course feel free to always come to you directly with any related concerns so you can make sure you are meeting their expectations, but you are concerned since the email you received seems to be addressed to you personally and you would like to make sure any perceived issues can be cleared up appropriately.
If you are invited to talk in person about this ("come to my office"/etc), and if it turns out that this is about someone else, follow up with another email that thanks the manager for talking to you about it and for them clarifying that it wasn't about you or anything you had done (don't, hopefully obviously, mention anything about anyone else, if they reveal anything of THAT nature: keep your "thank you" email firmly contextualized in just yourself), or whatever information they do divulge as it relates to you specifically: for example, if they say "this doesn't constitute a formal performance warning letter for you" include that wording in what you send them.
Save hard copies of all of the emails (including all responses) someplace where you will have continued access to them. Ideally the first email elicits a response such as "Oh it's not about you, I can't say who it's about, but you've always been great" and now you can keep a saved copy of that in case something does turn sideways later.
That might be more "confrontational" than you're comfortable being (because some people will always be inclined to see a formal response to a rather formal invocation as "confrontation"), but I've been burnt before taking someone's "oh it's just a regular/procedural/whatever thing and doesn't mean anything" at face value.