is the carport sturdy?

["Lee Daniels" <lee@automate-it.com>]

My dad is building a small carport; just enough to keep the sun off his car
during the summer. He sunk six 4x4's and is now working on the rafters.  Now
he says he wonders if the 4x4's are strong enough, since it wobbles when
he's on top.  I'm thinking that it will firm up when the sheathing is put on
the rafters.  You can see a photo of it here:
  http://www.automate-it.com/lee/carport.html

Any thoughts?

thanks, Lee