Thanks for all the support and advice everyone and I'm having hubby check at lunch for any nests of any kind. The only think I can think of is it came in off a tree onto the balcony and through the door there. It has a teeny tiny crack that hasn't been fixed by the landlord. Grr...

I just hope I don't see another one, I barely got any sleep last night! I am fairly certain it was just a garter snake...I sure hope so! I'd love to hear everyone's snake experiences. I've heard some at work today and I guess this is a fairly common problem.