I noticed that somewhere in recent VirtualMin updates it stopped including a virtual host's IPv4 in the VirtualHost statement of the site's conf.
This is Virtualmin 4.11.gpl on Ubuntu 14.04.1
This server has one default IPv4 and 3 additional non-default shared IPv4s. In previous versions of Virtualmin, when I selected one of these 4 IPs in the virtual host's IP settings, the site's conf would include the chosen IPv4, for example:
VirtualHost 188.8.131.52:80 [2a01:4f8:190:4373::10]:80
But now with the current Virtualmin it shows the private IPv6, but the IPv4 stays unspecified:
VirtualHost :80 [2a01:4f8:190:4373::10]:80
Meaning that the site will respond to any IPv4 rather than just the one intended to be assigned to it.