File stays locked after closing file for specific user

I have a particular file that when one specific user opens it and closes it when another user tries to access it it reports that the file is still in use. I ssh into the NAS and run lsof and grep for the file and it does show it as open, though the user is listed as root, not the user who had it opened before. I can kill the process and the other user can then access the file, but I don't want to have to do this every other day. Has anyone else experienced this?