It was Bob. There are actually three versions. The original without a stamp, the original stamped "Original" and later printings.
Here is his post...
"This is what I think. I have no first hand knowledge but, here goes: The publishers of Castle Rock newspaper noticed an increased demand for the first four issues sometime after the fourth or fifth issue was published. I think the increased demand was because of serializing the short story "Dolan's Cadillac." They still had some issues on hand of the first four issues so they stamped these remaining issues "Original" and stamped the later printings as later printings. But the bulk of the initial run of the first four issues were already in subscriber's/collector's hands and, of course, are not stamped as "Original." So, copies of the first four issues without any stamping at all are first printings. Does that make sense? The lack of any stamping is also an indicator of a first printing"