[Plugin: Bad Behavior] Bad behavior blocking Stumbleupon ?

I see that 12 visitor with a stumble upon referer

Referer: http://www.stumbleupon.com/refer.php?url=mysite..

Were blocked.

Bad behavior detect and block them ? Are they stumbler or a bot ?

User-Agent claimed to be Googlebot, claim appears to be false.

Is it normal ?

I don’t know if I ‘ll let bad behavior on my blog, it will depend on your answer.

http://wordpress.org/extend/plugins/bad-behavior/