If what you are saying is true there shouldn't be any problem. Regarding delay? Who knows? Sometimes we don't know how we may have got involved in a situation of interest to the FBI.
I doubt anyone can legitimately answer your question. That said, my guess would be no.
The answer provided is general in nature and should not be construed as legal advice as not all facts are know by the attorney, nor does the answering of this question create an attorney client relationship.
There may be some delays if your name is associated with some type of an FBI investigation, even if you were just questioned once. However, since you or your friend were never arrested or charged, it is more likely than not that your N400 application would not be denied solely on that basis.