Why are you using the result of the dot product as the angle (radians)? The dot product gives you the cosine of the angle (times the magnitude of the vectors, but these are a unit vector and a normalized vector, so that doesn't matter).
You could change your angle computation to
var angle = Math.acos(oldPos.dot(Template.Main.mouseCurrPos));
However, you may get the wrong quadrant, since there can be two values of theta that satisfy cos(theta) = n. The usual way to get the angle of a vector (origin to mouse position) in the right quadrant is to use atan2():
var angle = Math.atan2(Template.Main.mouseCurrPos.y,
Template.Main.mouseCurrPos.x);
This should give the angle of the mouse position vector, going counterclockwise from (1, 0). A little experimentation can determine for sure where the zero angle is, and which direction is positive rotation.