rsbm.I'm not sure what you mean. Who dished them out then? I guess you mean she didn't take an empty plate from a person and then hand them back food? instead she served onto plates the way a chef does in a kitchen of a restaurant and the people chose their plates like servers would, except they were serving themselves. That in itself does not strike me as odd.
To me it's a little odd. The usual method would be to serve people when they're seated, or in more informal situations hand them a plate directly. I'm really hard pressed to think of a social situation where plates are first laid out and then people come by and grab one.
I've seen caterers do it occasionally, but they have to serve dozens or hundreds in a short period of time, and even then it's usually just for dessert. Maybe if you're barbecuing and you take a bunch of burgers off the grill at the same time and yell, "Come and get it!"
But there is one advantage of this method. The portions are ostensibly doled out randomly, which would allay any possible suspicion that you could have adulterated the food on purpose.