Incorrect Artifact reveal announcement

Heart Attack, some time after I defeated the invading hordes the Mentor announced an artifact being revealed. I jumped to the last event only to stare into yet unexplored area. The artifact was indeed where I jumped to, but required the use of Prophecy to actually reveal it and no second announcement was made this time. Since that was real odd, I saved the game before casting it, then loaded and the Mentor again announced it when I cast Prophecy there, that hints the first time was actually glitched in a way or another.