Most of the times starting with the wrong premise is worse than starting with no premise at all.

Presumably said "spy" would presume that the code was found, and thus useless for them to retrieve, thus making the risk of discovery outweigh any benefit of retrieval. So the "spy" almost certainly wouldn't show up, and now they've been tipped off that the code may be compromised and the FBI may have become involved exactly in the manner they did.