FAO Storyline Engineers: Hover state not caching causing flicker of blank space

Within my Storyline project I have some hover states that use an animated GIF. I've noticed that once running via the internet there can be a blank space for miliseconds before the GIF loads. This could be expected, but the problem is, it continues to happen even after caching the GIF in the browser. 

On further investigation, it's because there is a cache buster parameter (?rs={random number}) added to the GIF whenever it is loaded, and is therefore loaded for the first time each time.

Can we not do this, or at least let me choose when this happens. What is the rationale for having this as the default behaviour? It's really inefficient and adding traffic that shouldn't be needed?

Thanks,
Sam