Activate Application Switcher (occasionally) still on after releasing CMD

Occasionally, after I have made the switch and have released the CMD key, the switcher was still on, as if the CMD was not released.

Pressing CMD one more time, the switcher went away.

It only happens occasionally. Therefore, I can't reproduce it. It just happened again a minute ago. But I can't take a screenshot of it, because pressing CMD will make it go away.

Is it expected behavior?

Just saw this phenomenon again.
I have released all keys and minimized all windows, and the app switcher is still on.