After setting setHover(true) on a markers, hovering a marker creates an InfoBubble. However, it does that each time the marker is hovered, even if it already has a shown InfoBubble. I assume it closes/destroys previous one and creates new InfoBubble, as you can see 'blink' on the InfoBubble.
Also, it would be nice to have an option to close InfoBubble when mouse leaves the marker area.