Asking on the RT is perfectly fine. The whole point of a basic service is so that you an get information needed for your flight, such as this (and not for getting traffic info!).
What it shouldn't be used for is as a replacement for checking notams. You should of course (and I assume you did) check the notams prior to take off to see if any activity was notified, but of course that doesn't mean that unnotified activity has started nor does it mean that the notified activity has been called off. So you are perfectly correct in asking about its status over the RT.