Not a serious bug - just a weird visual thing.
If I'm working on a Lightning component and, for example, change both the component and the style then do a build with the style still in focus, I can see in the Output window that it notices both files have changed and the Style tab changes fro "Style *" to "Style" but the Component tab keeps its *.
Also, sorta related, double-clicking on a line in Find In Files works as expected for Controller, Helper and Style but not Component. If you double-click a line for the .cmp, it will focus the correct primary-tab but won't switch to the Component sub-tab if it's not already selected.