I mistakenly shared configuration file of sth of my company in stackoverflow/reddit. My company found out immediately and fired me. How did they find out? Was it by looking at stackoverflow/reddit? I put them on pastebin and shared. AFAIK, pastebin isn't indexed by google. So,how would they know it? I'm really curious about the infrastructure in companies to figure these stuffs.
Have you considered the company may have monitoring software on the work computer? Logged access? Network traffic monitoring would let them know you went to pastebin and then it could correlate with your post time. There are lots of ways this could happen, which is why it's important to be professional with work equipment at all times.