Odd behavior - Grey background and spinner

I have an app that I am writing.

It has a timer that updates the screen with the time every second.

Every once and a while (several times a day, no pattern), the busy spinner and grayed out background will come on screen but the time is still incriminating and I see activity in the chrome console “qx.ui.core.queue.Manager: Flush Completed:…”

I see this behavior on my Chromebox running chrome.  There are no errors that I can see.

If I hit the refresh button in the chrome toolbar, the app goes back to running normally and the form that I have up and running.

Any idea what might be causing this behavior?

Thanks,

Shawn