Constant out of focus video recording topic

I don't record video much with the Z3 up until now, but when I was recording (SA mode) my family opening presents on Christmas Eve, the video had trouble focusing. The picture would be clear at one point, then blurs out as if the camera has trouble focusing at a point, becomes clear again, and repeats. I was filming from a distance in a bright-lit living room--basically not moving at all. Anybody experience this on their Xperia Z3?