Very likely, unless.
As with anything written anyplace, if one is 'repurposing' those writings without getting permission from the original author, and/or acknowledging the source, one may be plagiarizing.
Because of the internet, it is done all the time. However, if the source feels it was damaged in some way, ethics, laws, trademarks, patents, copyrights all come into play. It is a slippery slope: do the right thing.