Twitter revealed some users' location data, even after they'd asked it be deleted

I and others received this warning from Twitter on Oct. 25.

Twitter alerted an undetermined number of users on Thursday that it had inadvertently -- but temporarily -- revealed their location data, even though they had directly requested that such information be deleted.

I know because I was one of those users. I received the above notice as a pop-up at 8 p.m. ET.

In a notice titled "An issue affecting your privacy," Twitter revealed that it had discovered a bug which allowed users to search for Tweets by location even after the writer of those Tweets had previously selected "delete location information." The deleted information remained searchable for seven days after the delete request, as if there were some kind of 7-day hold on removing the information.

A notice below the delete request button does warn users "These updates may take some time to go into effect."

The issue was discovered Oct. 10 and fixed by Oct. 12, the firm said.

A Twitter spokesperson stressed that this issue only impacted people who enabled "sharing via location." The spokesperson did respond to a question about long this location data issue had been in place.

Many Twitter users may not realize that Tweets can be searched by location. On Twitter's advanced search page, one potential criteria is "Places." Users can search for Tweets posted by people who are near them by enabling this option, or they can pick other locations to narrow a Tweet search.

Twitter says that Tweeting with location information is disabled for users by default, but it's worth checking to see if that option is enabled for you. It's very possible; if you've ever Tweeted with a location -- even once -- Twitter then goes on to add a "general location" for every subsequent Tweet, until you actively turn off that option in settings.

Here's how to do that: Under settings, then "Privacy and Safety," make sure the box "Tweet with a location" is unchecked. There's also a button to delete all past location information. It's a good idea to use this option while you are there.

Delete your location information here.

Location data is particularly sensitive for some users. A stream of Tweets (or Facebook posts) that reveal location could help someone reconstruct the whereabouts of the writer over time. Location-tagged Tweeting can be useful, too: As one example: "Hey, I'm at the conference, in this coffee shop, if anyone wants to say hi." But in general, users should be extremely careful when they share such information with any digital company, and understand that a seemingly innocuous action today might have unexpected implications tomorrow. Also, as this story shows, even though a company says it will delete your private information upon request, it doesn't always work out as planned.