all JUnit tests run green, but final status bar is yellow

Hi All. I have a set of tests that all pass, but the final status bar in the upper right of the Run panel shows yellow (see attached). I've whittled the problem down to one test, HelloServletTest, which is in its own folder, "servlet". When I run that test by itself, the tests all pass and the final status bar is green. However, when I run the containing folder, the bar is yellow. I'm running by right-clicking the file or folder and selecting "Run __". Any ideas as to why the yellow? A bug?