Reggie Bush underwent an MRI exam on his left hamstring Monday after he spent all three days of the Saints' rookie camp limited to watching or participating in half-speed drills. Bush and Saints coach Sean Payton so far have shown only minimal concern about the injury. "It feels good, but obviously not 100 percent," said Bush, adding he could not recall having a hamstring injury before. "That's why we're taking precaution." Bush said he expected to be "100 percent" by the end of the week, well ahead of the Saints' full-squad minicamp slated for June 2-4.