Updated version of zipped Storyline file is much larger than previous version

Hi, I have a Storyline 360 file that is 79 mb. In July I first published this project for web and the published zip file was 189 mb. Yesterday I made a small edit to the project (text only) and re-published it for web. The resulting zip file is 430 mb. There are tons of images in the project, but no videos, and the publish optimisation settings are still set to "standard." Any ideas why this could be happening? I'm currently on version 3.48.24159 - it upgraded before I edited this file yesterday.