Was Ned ryerson scamming Phil by feigning familiarity?

Nope. Phil had forgotten about him and barely remembered him simply because he didn't have much use for him. Ned also mentioned dating Phil's sister and called her by name (Mary Pat?). Unless he was a world class stalker, how would he have known that before running into Phil by pure chance in Pennsylvania?

I don't find it that unlikely. I work at a Kroger store and often have people coming up to me saying they remember me from highschool. But I don't even remember them.