Flashing watch face

This is probably a very silly question. I just noticed that if I look at my watch face at just the right angle it seems like the brightness is flashing. It is almost like having the reflection of a fan spinning overhead. It's not noticeable from most angles. Has anyone else seen this?
I can't go in and look at the code for Anton Clock right now but I am wondering if I am just seeing it refreshing.

Is it under artificial light?

I've seen this occasionally, and as far as I can tell the lcd changes its optical properties very slightly depending on the power state of the watch. It's too fast to be a display update and the blink rate goes up dramatically when I pick the it up and the watch starts querying the accelerometer more often looking for a "twist" gesture.

Yes. I was at the airport when I noticed it.

Yes, it's the LCD refreshing - it inverts itself every so often in order to avoid 'Ghosting' which happens if the panel stays in the same state too long. I think it's more noticeable under polarised light.

When the backlight turns on it's much more noticeable so the refresh rate goes up far faster (but then the power usage isn't a big deal). To keep the power usage down normally the refresh has to be done at a reasonably low rate.