Is this an expected and normal VSync behavior ?

Hi ! I saw this question unanswered for quite a long time now (2015) and I believe it's causing jitter. Is it normal for VSync to take only 0ms once every a few frames (as showed in the image) ? I expected VSync to make my framerate match my screen's refresh rate, making my game run at 60fps and not at more or less than 60. ![alt text][1] [1]: /storage/temp/128905-profiler.png