I think that telling a denied target is in the statute.
I'm looking now. But think about it, if that is in there, it is a stupid requirement.
Targets of physical searches (not DENIED targets, but actual ones) have to be apprised that their premises were tossed.
link to Bryan Cunningham's letter to Specter, Leahy, et al.
http://www.morgancunningham.net/downloads/article_22.pdf