That does not sound right. However, most of us on the forums are API specialists and not content specialists.
Therefore, please raise a Content query with our Helpdesk to see if they can provide an explanation of the sequence num discrepancy.
Please include as much detail as possible for the two ticks i.e. the ones with seq num 30 and the 16. If you have the full payload for each tick include that in the ticket as an attachment.