I'm guessing most candidates don't have a lot of open source contributions, and "more open source" is one of the standard lines when they don't want to really e

I'm guessing most candidates don't have a lot of open source contributions, and "more open source" is one of the standard lines when they don't want to really explain why they passed on hiring. Don't read too much into it. As an entry level applicant you're only getting a small fraction of anyone's attention and will need to apply Hanlon's razor to interpret most of your interactions.