I go with the idea that if the person didn't know the raok was over, then asking is fine... after all, how would they know otherwise?
On the second hand... a lot depends on how you 'closed' your raok.
If you said something like 'No more free shrimp.', then it might be appropriate if someone PMed a question if you would be willing to sell them some, but NOT really respectful if they were asking for free when you arn't giving any more away.
However, if you said something like 'No more for now.' then it would be decently acceptable if they asked if they could be put on a waiting list if you ever deside to do it again.
Really I think it all depends on the wording of the request as well... A polite asking if you have any more you want to give away, or a blunt push to get something for free.
I guess it would all have to be considered on an individual basis.
Rammble-rammble-rammble.... I need some coffee. LOL