It would certainly imply they believed the world was round, but not that they knew for a fact (Through successful circumnavigation, or mathematics). This is a good thread to read through, the world's roundness was well-accepted by the Medieval Christian church, which was supported by the work of several Greek philosophers.

https://www.reddit.com/r/AskHistorians/comments/4fi9q6/teacher_says_that_the_earth_being_flat_is_one_of/