It hadn't been long since Marcus' conversation with Jeremiah and the handing over of the Alpha rank; this was not something that could be left for too long. If the pack dynamic was changing, particular the hierarchy, then the rest of The Sworn needed to be told sooner rather than later.
And Marcus did not like leaving important news while he mulled it over. He waited at the Den for the rest of The Sworn to arrive, a cup of slightly sweetened tea warming his hands. He had had time overnight to think things over, and how this might effect the future. He was calm.
After what had happened recently, things could not get much worse without really trying to screw themselves over.