[xg15]

I'm actually under the impression that LinkedIn will log in to your email account if they can.

That seems the most likely scenario to me to explain the article. Maybe they try to log-in with your email and linkedin password on the chance that you used the same password for both services?

Then again, on gmail, this should trigger a "login on new device" warning and shouldn't be possible at all if two-factor-auth is active.