My wall outlet is making a hissing noise, should I be concerned?
If the circuit makes a 'hissing' noise as soon as load is applied, then you definitely should check that outlet for a problem. 

Shut off the power at the breaker. Confirm that the power is off using either an electric light plugged into the outlet, or by using a Non-contact voltage tester. Unscrew the faceplate of the outlet, then unscrew the outlet. Examine the wires for heat damage or signs of arcing. I'd probably just go ahead and replace the outlet. 

This is definitely something you should worry about; I'd expect to see something like this: 



If you don't feel comfortable doing that, call an electrician.