I don't know what discipline you are studying, but I can give you input from my field of perception.
As a clinical social worker, it is my opinion that it is best to share what you have learned with the patient. I firmly believe in the right of the patient's self determination. In this way, the patient has the right to know what possible issues may cause problems, and then can choose whether he feels it is an issue. Most treatment plans are developed with the patient's interest and goals, as well, so it will be important to gain his commitment to work on the issues. The fact that he does not reach the clinical level tells me he has fairly rational thought content, and would be able to handle the truth about what you have learned.
I believe that by arming the patient with knowledge of what you perceive as possible or potential issues, can help to circumvent these issues. With some depression, there may be psychotic features such as paranoia. This should be addressed as part of the problems to correct. The patient may also have some insight about the paranoia, but may be too paranoid to say anything about it! By you bringing up the issue, this may help him to speak freely about it, thus lessoning the paranoia, and normalizing his feelings about it.
This is, of course, only my opinion! Mary, please let me know if you have further questions. Thanks, Gina