Old wives' tale or not, I've always been taught the folly of storing warm sauce. I only brought it up because the initial post was about getting rid of excess moisture in pizza sauce. The best way to do that, for me, is to allow the tomato sauce some time to thicken in the refrigerator (preferably overnight).
As a rule, we do not cook our pizza sauce. However, I realize that some members of the forum do, so I added in the line about making sure the sauce was not warm.
If I was wrong to perpetuate an old wives' (or old pizza man's) tale, I apologize. However, I felt I was speaking from experience. Isn't that what this forum is all about?