Virus ?

Ignore it. Any pop-up whatsoever that claims you have a virus (or that your Apple ID has been or will be locked) is a scam, attempting to trick you into entering your password and ID so that they can steal from you, or to sell you expensive and completely useless (and quite likely malicious) software. Never ever follow up any links or phone numbers in this sort of thing. You don't have a virus: no-one could detect one remotely even if there were any affecting Macs. If you can't get rid of the pop up force-quit Safari and restart it with the shift key held down.

Could be unrelated but in our case, the popup occurred while reading an article on wired.com

Please read Phony "tech support" / "ransomware" popups and web pages.

If that describes the web page you encountered, and you successfully navigated away from that web page, then no other actions are necessary or justified.

To reiterate:

- should I be worried

No.

- what actions should I take

None. Acting upon any information appearing in the fraudulent pop-up is what leads to trouble. Whatever it said doesn't matter, because it is an attempt to defraud you one way or another.