Nobody in the world has ever caught HIV from exposure to blood in the environment, including contaminated toilet seats. HIV cannot survive in blood or other body fluids once it dries. Even getting wet infected blood on the skin is zero risk for HIV as well. On top of all that, stiastically it is unlikely that the apparent blood came from an HIV infected person. If you would like more details about the absence of risk from events like this, read a few of the many threads on this forum with quesitons like yours. The search function isn't very sophisticated, but if you enter the word "environment" in the search field, you'll find over 100 questions and replies that discuss these issues.

So no risk, no worries, no need for testing (asssuming no other risks for HIV).

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD