60k is a "young" g35 engine... and he probably really only had to do general maintence as my last two Gs never broke down. I had my 2005 g35x up until about 72k miles and it ran like new, and I am harsh on my car tracking it every chance i get. they only thing i can immedialy think of to watch out for or ask about is a oil leak problem on to one of the spark plugs... i believe it was the 2006 coupes. (you probably saw that in the FAQ section)
if the seller halfway maintained his G 60k is nothing to the engine. Now i would ask about the transmission fluid being change at least once in that 60k miles. if it hasnt been changed thats an extra cost you would need to factor in. (make sure you get the Matic S transmission fluid, NOT the Matic J as it was replaced by Matic S)
wait you said coupe, well clutch fluid being changed...
if you care, id also change the rear differential fluid at about 60k also.