So his original owner texted me last night asking how he was doing. This makes me feel like she really does care.
I found out his parents are both Chihuahua's. She even sent pictures of them to me. His birthday is in February, so he is 10 months old, not 8. Still a puppy though!
She did take good care of him. His coat is nice and shiny and he is basically healthy.

I am taking him to the vet Thursday night to get his vaccinations started. My co-worker is going to take him on Friday (hopefully this goes through) and keep him through the holidays for me. We will be going to a bunch of different places over the holidays and I don't want him bouncing around like that. I'm hoping her and her husband fall in love with him (like we did!) and will want to keep him. If not, she'll give him back to me and I'll continue to search for a home for him.
I also found out my vet does rescue rates for rescues. So if I do get him back I'll take him in to be neutered before finding him a home.

Let's just hope he finds his home over the holidays with my co-worker!