We are in the process of migrating workers from travis-ci.org to travis-ci.com in preparation to fully shut down .org (or rather, make it read-only) on December, 31st.
Unfortunately, this might happen as a result — if we see a job stuck in a queue for more than 16 hours, we will review this on a case by case basis and possibly cancel the job to ensure resources are not being reduced across the platform.
Here’s a FAQ to clear things up: https://docs.travis-ci.com/user/migrate/open-source-repository-migration#frequently-asked-questions.
You may want to consider migrating across to .com sooner rather than later, or consider building at a quieter time of the day if remaining on .org for a while longer.