Unfortunately I only have an Apple tablet that I can test on and it seems to work fine for me. I tried testing on Browserstack and when I double-clicked the menu, the drop down did appear. I’m not sure if this is exactly the same functionality as on a proper device though.
Does the Quark Demo site do the same thing? How do drop-down menus work on Android devices, do you simply double-tap them to open them? Does the menu work differently if the top menu item (eg. “Services”) isn’t a link?
I found a topic on the WordPress forum about Android and the drop-down menu in Twenty Eleven and in particular, the last post on the page. He mentions that “it’s not that the dropdown dosn’t work, just that the trigger for the dropdown can’t have a link attached to it.”. As I mentioned above, unfrotunately I don’t have an android device I can test on so I’m not exactly sure of how they handle drop-downs like this.
Let me know if any of the above helps though.