What would you-person next to you on a plane acting nervous/odd?

I had to travel today for work. I got on the plane and a guy was in my seat. I nicely told him that my seat (I'm not sitting in the middle since this seat was reserved a month ago for me).

He apoligizes and moves over. Then I noticed some writing on his hand. He seems all agitated and nervous. I find his blackberry he dropped and this seems to stress him further. He keeps checking his bag under the seat in front of him. He is acting really suspicious.

I start thinking I'm going to let the flight attendant know. It is really beginning to freak me out. I am pondering this in my head and keeping my eye on him (from the corner of my eye of course). We roll out from the gate - I figure it is too late to notify a flight attendant and something keeps me from it. I plan on jumping him or using the point of my shoe to wack in his head if he tries anything.

He keeps reaching into his bag so I blurt out - what do you have in that bag? He says .......a cat! Then we begin talking pets.

Am a paranoid or what - thank goodness I didn't report him - I think he was nervous about his pet.