Grade Of Fish (For Sushi Or Sashimi): This is a marketing term referring to top quality, fresh fish; you need to ask if it has been frozen for parasite control (more about that in a moment). There is no official FDA Standard of Identity for a “sushi grade” or “sashimi grade” of fish. The FDA does, however, have guidelines for the handling of raw or undercooked fish, including sushi and sashimi as well as ceviche, cold-smoked fish, drunken crabs, green herring, herring roe, lomi lomi, poisson cru and cooked dishes that are served with raw interiors. It suggests that food handlers ensure the destruction of microscopic parasites that can cause gastrointestinal infection by freezing the seafood (there are options, e.g. at -4°F (-20°C) or below for 7 days, at -31°F (-35°C) or below for 15 hours, or at -31°F (-35°C) or below for 24 hours. You can read the details here. The irony is, most people think that “sushi grade” fish is the absolute freshest fish. But it isn’t, because to protect the consumer from parasites, much of it has been frozen. Some fish—mackerel and salmon, for example—are known to harbor higher levels of parasites than others, but these days almost all fish served raw are frozen first.
I would directly speak to the preparer about the above standards.

My understanding is that "sushi grade" is either immaculately fresh or has been frozen at very cold temperatures, dry ice or lower, for a longish period of time (maybe a week or so, to kill parasites). So, I've read that most all sushi in restaurants has been previously frozen, but maybe this isn't true at some very high quality restaurants.

Notice that even the frozen fish must be quickly eaten upon thawing to maintain quality and taste good. "Sushi grade" fish at markets can sit out for some time before someone is willing to pay the higher price. When I buy fish to make sushi at home I usually go to a Japanese market (I'll add that I try to live in towns that have Japanese markets for this reason). I'd order over the web if you don't have a market in town.

On the other hand, I've know people who buy salmon from the local chain market and make sushi with it. The argument against this is that the ice displays at markets is a great place for parasites to travel around and sample the fish! Swordfish, for instance, is famous for giant worms... once I learned this I've never had swordfish again.

Whole Foods Market sells "superfrozen" salmon for raw consumption. However, farmed salmon is generally safe. Wild salmon, if never frozen to minus 40 degrees F, should be thoroughly cooked.