I doubt the Americans are worried that any sensitive technology has been lost. The RQ 170 doesn't have the radar absorbant paint or ducted exhaust to mask the IR signature. The radar might prove to be useful if the Iranians don't already have access to AESAs. More important, I would imagine, is the knowledge that an aircraft with a small radar cross section and flying at a relatively high altitude is vulnerable to Iranian AA weapons.
Brazilian head of UN peacekeeping force in Haiti dies of heart attack (Reuters)
from the article: Iran state television displays 'downed U.S. surveillance drone'