Is somebody able to shed any light on the following?

A student this morning was logged into one of our Mojo sites (an online learning package - Mojo version 2310) on her home computer. When she logged in she ticked the "Remember me on this computer" checkbox. Later that day she came into the University and logged into the same site. She was working through the site for a short time when a popup appeared saying that she was locked or logged out (sorry I wasn't there at the time so am not sure which) and advising her to contact me (I am a site Admin and I created the page she was on when the pop up appeared).

Does anyone know why this occured? Sorry to be quite vague but I am only reporting what was reported to me second hand.

Many Thanks

Tracey