It was an ending to a first half rife with confusion on the part of the referees, the Lions and the Saints. Zach Strief stated in his post game interview an offensive lineman does not have to report each play once he has initially reported. This video clearly demonstrates Senio Kelemente declared his eligibility but there was an intervening, legal time out by the Lions between his declaration and the subsequent play.
So, the question is whether the rules require a play to report again after a time out or report for each play. The 2015 rules read:
So, it would seem Senio Kelemente would have had to have reported as eligible again. We reviewed the coaches film but it does not show pre-snap interactions between players and officials. So we cannot tell if Kelemente reported but the officials neglected to inform the defense.