Not sure if anyone can shed any light on this issue.
I have a site using Gridiculous, and the main menu is a custom menu with parent and sub pages.
When I view the menu on a mobile device, I can select a parent page from the menu, which then opens a list of sub pages underneath that item.
However to open the parent page to view its contents I can only hold down on the menu item, and then wait for the device to give the option to open in a new tab.
Viewing on a Windows Phone 7 device. Haven't been able to test on anything else.