If it bled that well, and you washed the scratch then any kind of infection is not likely, and tetanus is VERY unlikely.
Tetanus shots are given as a precaution for most any kind of cut or scrape. Tetanus spores are an 'anerobic' microbe, meaning that they only will reanimate into an infection causing pathogen when in the ABSENCE of oxygen. That's why we all associate tetanus with the old 'stepping on a rusty nail'. A narrow puncture wound pushes the spores deep up in the body and a narrow puncture like a pin or nail doesn't bleed much, generally.
However, having said that, if you are due for a booster I'd go in and get it. Tetanus is pretty common in the environment, and is particuarly found around the manure of farm animals - hence the reason they are recommending a booster since it was a rooster that scratched you.
Frankly, I'd be MORE worried about a plain ole bacterial infection from the scratch than tetanus, but I'd go in and get the booster anyway, ESPECIALLY if it's been 5 years or more since your last booster.