You were correct. I just found this article online about old injectables.
Quote:
The concern is not the dose not working, the concern is the danger of the vial no longer being sterile. Other guys here are saying they would/have taken the risk, but please be very cautious with old injectable drugs. Any injectable vial expires 28 days after it is first ounctured, even if it has preservatives (an extra substance that kills bacteria). After that, bacteria can slowly grow in the testosterone vial. You may not ever personally have a bad infection as a result, but patients do come to the hospital with terrible skin infections, which can even spread through the body (sepsis). While rare, these types of infections can be deadly. As a medical professional, I would never use an open vial after 28 days.
If you do understand and accept this risk because otherwise you may delay a dose, you should know that the risk increases with every time the vial is punctured.