Guinea Pig Behavoir - jumping

Question
We have had our guinea pig for 2 months now, he is about 5 months old.  Usually when we get him out, he is calm and will just sit or walk around his floor playpen.  Lately, he has been a lot more adventurous, wanting to walk around the house.  He went under our rocking chair and would not come out.  He was jumping and running around in a way I have never seen and would not let me daughter pick him up.  She ended up crying.  We eventually got him out and put him back in his cage.  

Is this normal?  Is he just getting new behaviors since getting older?  I wouldn't call him aggressive but it was just a lot more aggressive than he has been in the past.

any help would be appreciated.  We are new to all this.

Answer
Hi Nicole

It sounds to me like your piggy has been popcorning. This is basically an indication that he is just having fun roaming around the house. He didnt want to be caught as he was enjoying his freedom. This is nothing to worry about at all.

andy