catrunner,

The question you pose is one that only you can answer. No one reading your post can know to what extent the record of the polygraph you took four years ago at an unidentified college in an unidentified state might be shared with other agencies.

The paperwork you signed at the time might include information about the extent to which your polygraph results, or details of your application more generally, may be shared with other agencies.

What is certain is that an admission to having previously failed a polygraph "test" is highly prejudicial and may make an accusation of deception or countermeasure use more likely.