Was I creepy/weird?

A guy at work and I have been getting along great for months now. We flirt with each other, laugh, he stops by to chat frequently, we make up reasons why we "need" to work together, etc. It's to the point that other people have started to notice. I thought it would be OK to add him on facebook, but after several days he didn't accept, so I canceled my request. Now he seems to be awkward/distant. I tried asking if anything was wrong, but he said no. Did I make a big mistake?

Was I creepy/weird?
Post Opinion