When discussing The Replicator they talk about old cases that neither Alex or Rossi were part of, even though it's the current team that's being stalked, and somehow fail to notice that The Replicator has only replicated cases they worked on since Alex joined the team. The Silencer was Alex's first case with the BAU and the first one The Replicator copied.
Hotch says "fewer than twelve hours". A man of his education would know that, since time is a continuous value, it should be "less than twelve hours".