With ulcerative colitis should i worry every time blood comes out even if its a little?

Yes: Requires careful monitoring and surveillance.

Depends: If you are on maintenance therapy and have no other symptoms, ie well controlled uc, probably nothing to worry about unless the bleeding increases in volume or frequency. Notify your doctor who is managing your uc and ask their opinion. If the bleeding is new, it may indicate that you are the onset of a flare and for sure need to discuss with your GI doctor.