Not sure if my FB website pixel is installed correctly.

It looks as if the website tracking pixel I installed in the header php is working according to my Facebook 'Audience' tab. However the number of visitors in my Facebook Audience is increasing in increments of 30. Is this normal? Also, there is a chrome extension called Facebook Pixel Helper and its saying there is no pixel installed on the website? would really appreciate if someone could confirm if the pixel is installed correctly.