Tenant may of forged my name?

[William Pickett]

To have to power cut on in a tenants name they must get a paper singed by me(landlord) and them(tenant) and carry it to the power company in town to have the power cut on in the home and billed to them.  

I saw the power on and called the power company, they said they received my paper with my signature on it.  The power is on in someone else name. May be the tenants father, uncle, friend doesn't matter.  What bothers me is someone forged my name.

How should i proceed?  Rent is due this week, so should I see if he pays the rent and go along like nothing is wrong?  Or should I mention it now or before I get paid?  I have never had this happen.  Need pockets wisdom.