In some applications a slight buzz may occur. This will not cause any problems but I'd suggest you try a different switch if you feel unsafe about it. The reason it buzzs if because you are dealing with A/C (alternating current) voltage. This alternating current can sometimes cause transformers, coils and other electrical devices that use windings (motors) to have a slight buzz.
Once again, if you feel unsafe, please replace the switch!

Chris Couture