Here's the latest official word on the FNU issue.
My company recently mailed that US Consulate has stopped issuing Visas without proper bifurcation on first and last name.
In my case, I just have my First Name "Rahul" in the Given name in passport and have FNU Rahul in Visa.
Now I may face problem when I go for restamping, So I am thinking of changing my Name in the passport.
But have to get it changed in many other places too (Just in case further problmes arise in future) - School and University Certificates,Bank a/cs.......
Its tough. But have to go thru it, there's no other way...