In the northeast there is snow, sleet, slush, ice and everything in between. Not to mention the worst offender, road salt.
Underbody rust is therefore much more prominent than on a western or southern car, unless the owner religiously washed the undercarriage, and kept the car in the garage. You don't necessarily have to be worried, but just be aware of that.
One thing you might look at is the fuel filler neck; over time, and particularly with all that yutz exposure, it might be a good thing to replace with a new OEM one. Otherwise, if you feel ambitious, just look underneath for bolts/nuts and such that you might want to swap out. Exhaust parts are always some of the worst, too.