Lines appearing on PDF save

Hello,

I am not really used to working in Illustrator but was tasked with creating a logo for a project I am working on atm. I used the expand tool on the gradient in order to make it scaleable and this might have been a bad idea. Everything looks fine in Illustrator but when I try to save it as a PDF file it displays quite differently, with lines of different colours showing up.

I have attached the PDF file to better show the issue I am having. If anyone could provide some insight into what I am doing wrong I would greatly appreciate it. I would like to also attatch the AI file but I get the following error when I try to attach it : The attachment's logo_blue_rdy.ai content type (application/postscript) does not match its file extension and has been removed.