Huh... it usually happened when I interact with him before a talk event (Where he'd say "Hey [insert name], can I talk to you for a second?") but I can't seem to find a specific instance anymore. Was that fixed?
Ah! I see. Yes, it's fixed now in an update. Unfortunately for Itch games, you have to redownload the whole game to get the update. Unlike steam, it doesn't get automatically updated. Just be careful because you might lose your current save file with all the changes.
Thanks for reporting the bug though! I appreciate it.