Nerve rattling? Let me go out on a limb here and assume that the surveillance plane had a clear radar picture of the Russki aircraft before it got anywhere close. If you didn't see it until it was there, no warning, that would be nerve rattling. More like pi$$ed off at the bad manners than rattled.
Just FYI: P-8 doesn’t have A/A radar. “The P-8A Poseidon is an aircraft designed for long-range anti-submarine warfare; anti-surface warfare; and intelligence, surveillance and reconnaissance missions”
http://www.boeing.com/defense/maritime-surveillance/p-8-poseidon/