Facebook has fixed a bug in its iPhone app that spooked some users by inadvertently turning on their cameras.

The bug caused the camera’s view to show up in a strip on one side of the screen when users tapped on photos. Facebook says it was accidentally introduced as part of an update to the app launched last week.

The company fixed the problem with another update after Web strategist Joshua Maddux drew attention to it on Twitter. He said it made him concerned that Facebook could be using facial recognition to see users’ reactions to posts.

“(E)ven if it’s a bug it shows that they can access and keep the camera behind something,” Maddux, who owns the Web design firm 95Visual, tweeted Tuesday. “That’s the part for me that’s crazy.”

But Facebook has no evidence that any photos or videos were uploaded as a result of the glitch, a company spokesperson said.

Apple has approved the app update that repairs the bug and users can now install it to fix the problem, according to Facebook.

“We’ve confirmed that we didn’t upload anything to FB due to this bug and that the camera didn’t capture anything since it was in preview mode,” Guy Rosen, Facebook’s vice president of integrity, said on Twitter.