Not necessarily. As I said, I don't think it's the case, because I don't think they were mailing the comics (and therefore wouldn't care about the numbering continuity), but given Waldman's well-known "what do I need copyrights for?" stance, IF they were mailing books, I wouldn't be surprised if they made up the numbers and only changed to #1s when caught. That might even explain the #11s, hoping to sneak under the radar, if the Post Office were a factor. You might get a burst of #1s with a few rogue teens hidden, hypothetically.
But back to my actual question, is there a spreadsheet of issue numbers with their cover dates? Browsing the GCD was never designed for this sort of investigation (there's no reason to imagine it being a major use, after all), but I can't help noticing, for example, that a lot of #10s appear to have been published in 1963. Were all of them? Were they the same month?