Make sure that you use "shift reload" on your browser to make sure that the image is not being cached by
your browser. Having said that -- yes the image is also likely
cached on the machine as well. There is some effort made to insure that this image
is "current" but since you are doing something a bit outside the standard box
it's possible that in this case the refresh isn't behaving properly. It would take some experimenting
to figure out exactly what the problem is.