Random little piece of black tape stopping my guitar from being properly grounded??

I have a schecter sls something something and opened it just to see what it looks like inside and there was just a little piece of black tape over the 3 way blade switch. When I hold the cover on the back, without the tape, no hum. With the tape, there is hum. Is the tape stopping anything bad from happening orrr what could possibly be the point?