That's interesting. I happen to be reading Miller's Church History, I see it reference from time to time so I thought it might be good to look at, and on pg 380 came across a note about a man named Clement who was condemned at the synod of Soissons in March 744. He was condemned because he held to the belief that "no councils, writings, decisions of the church that are contrary to Scripture had authority over Christians".
Here is a case of a man being condemned 800 years before the date you believe Sola Scriptura emerged. The point being that belief in the 5 Solas has always been around, it's just that at various times it conflicted with the goals of the dominant church of the era.