I find the BBC online news much more detailed then others:
http://news.bbc.co.uk/2/hi/uk_news/6981541.stm - 8 bear issue
The surprise factor doesn't have to come from radar stealth or lack of a flight plan; the BBC news stated that the two 'July bears' "strayed south from their routine patrol pattern off the Norwegian coast and headed towards Scotland."
They just simply "forgot" to mention the some details of their intentions in their flight plan.
No-one not even Russia would want a nuclear war - it's pointless, it would be like shooting yourself in the foot.
Quite true; one of the points Ronald Reagan pointed out to the Soviet Union to end the Cold War.
I bet more of these "accidents" happen all the time.
In my opinion, Putin is acting like some small (and hairy) child desperately looking for attention. Well, I must admit that it's working; Russia's first time on the front pages for some time now.
What I would like to know is the next bear's reaction if no Scramble satisfies their call for attention. A small child (hairy or not) would get frustrated.