Dressed as Ares, being so important at the Sci-Fi Conference, Heath didn’t know or care when David left, or where he went.
Focused on himself, his appearance and presentation, relishing how the eyes of the fans touched him, wasn’t conscious of much beyond himself.
Days,weeks passed, and he didn’t notice that David did not contact him.
It is only looking back that he realised that David never contacted him again, and he had made no effort to contact David.
Setting it in a time frame it was a year from that Conference that Signs of the Zodiac was canceled. At the time, he saw it as a shoulder shrug, assuming there were cabinets of roles that he would be offered.
But that didn’t happen.