I know, this will be lame and stupid, but... when I saw it I can't unsee it now. (
So, when you hover over elements which get hover class (seriously, why you don't want use simply :hover pseudo-class? It's much more reliable and simple...), one of them is dropping. In this case, widget button up. When I hover, he gets hover class and yadda yadda. The game timer goes further by second and class is lost, even if I hover the cursor over it.
So, yeah... don't ask how and why... just fix it, please.