This is a good question one I can't really answer but I'll give it a try anyway. I studied a bunch of works on medieval history during my Bachelors in History.

During my university education some professors claimed it has always been a problem. There are works on the "panic in the medieval world" in the year 1000 and I think the year 666 (not sure on that one though).

I don't remember learning about there being wide spread panic, but chroniclers did mention fringe groups and religious zealots believing the end of the world was near and the return of Jezus. The Apocalypse was offcourse a great catalyst for these guys.

Other more recent works will often dispute the chronicles mentioning panics and general fear. Especially the ones that claim a widespread panic was reported.

However! The existence of these works alone, often written in the later medieval area up to the 1800's pretty much confirm that a general idea of the apoclaypse or fear of the millenium (999, 1999) can be considered a "thing". Exactly what you are asking. There was at least an idea of a panic or a fear of the apocalypse gripping some people but certainly no widespread panic.

While I was working on the chronicles of Albertus von Aachen, as a research project, the fall of Christian Kingdoms in the east and the conquest of Jerusalem by Saladin was also considered by some as a sign that the end of the world was near. He mentions this as a sidenote, but it again confirms that some people always where read to jump to conclusions about the end of the world.

There is a similar question already asked here - http://www.reddit.com/r/AskHistorians/comments/1m1n4s/humans_and_the_end_times_have_we_as_a_species/