Virusses don't just hang around on toilet seats, etc. and shouldn't be able to survive for months outside the body. If you want to really rule it out, wait several months after the exposure and have an antibody test for the heps. It takes several months for the body to form antibodies and so for them to become detectable in the blood.
The likelihood of any needle stick being infectious is between 0.5 and 4%. It’s even more unlikely given that the needle is that old; it’s believed that the Hep C virus can last up to 4 days on environmental surfaces. Nevertheless, you should call your doctor Monday morning, and explain what happened; he/she might want to establish baseline testing from you.
Take care—
Bill