A faint line on a pregnancy test can be an early sign of pregnancy, but it is important to keep in mind that false positives and false negatives are possible. Factors such as the brand of the test, when the test was taken in relation to conception, and sensitivity of the test can vary results.
That said, it is a good idea to take it as a preliminary positive indicator and take repeat tests as recommended on the package inserts and consult with a medical professional for confirmation and further instruction, as they can assess other contributing factors as well.