If my blood results say "slight hemolysis, " what does that mean?

Nothing serious: Sometimes mild trauma can cause this. Sometimes if they used a needle that was too small it can also cause hemolysis. Unless it repeatedly happens, it's likely nothing to worry about.

Improper handling: This usually refers to a blood sample handled poorly in which some of the blood cells break open, releasing the contents into the serum and possibly altering the results of the blood test. not a problem for most analysis but the laboratory will usually inform your doctor if this can affect the results.