Roo attacking one hen!

[twilightNC]

I have 10 bantam chickens, 2 of which are roosters and they are about 6-7 weeks old now. They have always lived together and all of a sudden one of the roos (silver sebright) is acting like a total maniac to one of the hens. He pecks her, chases her, flies toward her and this evening I found her with her head hiding under some straw! I think she was scared!!! Is this normal and should I take him out?
Help please. Thanks everyone!!!
One more note-I did recently giver one other roo away to my FIL. Could this have something do do with it?

 

[wynedot55]

giving a roo away has nothing todo with the way this roo is acting.id pen him by hisself for awhile since he is being mean to a hen.an see if that calms him down.

 

[twilightNC]

Ok, any idea why he's picking on one hen?