I've had the same.
I treated it as phishing too, and didn't think any more about it, 'til you mentioned.
I'm sure I've not missed anything important, by binning it without a thought. I know it's not anything I'm genuinely subscribed to.
I noticed it was formatted to resemble a message from Facebook, so it occurred to me incompetent phishers simply forgot the name/logo of whichever organisation they were trying to pose as.
I get a few a week of similar design, purporting to be from Facebook. They either claim there are messages I've missed (hardly likely, as I check in quite regularly, but don't live my life there, so there are rarely new messages anyway). Or that they're sorry I'm having trouble logging in, and please click to get back in. Also obviously untrue, when I've been using it as usual, with no problem.
Very occasionally, I get a genuine message from Facebook, saying that somebody (not me) has tried to access my account, that it has not been successful, but recommending I change my password, just in case. Although these are genuinely from FB, I'm not sure they relate to genuine "hack" attempts, because there seems to be some dumb woman in the U.S., with the same name as me, who does not seem to be able to distinguish her own login details from those of other people with the same name.
She doesn't know her own e-mail address either, because she quite often signs me up for Walmart offers, and other drivel, and her friends periodically e-mail me as well!
None of it's threatening or harassing, so I've no reason to think it's a concerted campaign. I think she really is just thick, and hasn't noticed the e-mail she gives out to all and sundry isn't hers.
I wonder if she's ever curious why she doesn't get any replies. I've had flight confirmations for her, car-hire bookings - all sorts.