If you start the search and the list of search results opens, the element that “coincidentally” lies under the mouse pointer (if the mouse pointer is in this area) is selected. Even if you want to go through the hit list with the up/down keys, you seem to start at this preselected element.
In addition, the mouse pointer interferes with scrolling through the hit list because new elements are always selected by the mouse pointer and thus get stuck in the hit list.
This is also an issue on Mac desktop as of version 0.6.3.
To generalize this issue, the passive location of the mouse always acts as if it was a user intentional hover action.
In addition to the search issue described above, this causes tooltips to appear if any link moves under the mouse (e.g. you go to a new page using only keyboard commands and a link on the new page happens to be under where the mouse is). This both breaks keyboard navigation and also makes it so one has to move the mouse to get it out of the way far too frequently.
One solution would be to only respect mouse hover location when the user moves the mouse to a location, and then once any state changes (scroll, navigation, typing?) then the hover location is ignored until the user moves the mouse again.