Well, that is very cool! I'm also impressed that your 11 month old is talking already! (my boys didn't talk until after one years old).
I had a story told to me once by someone that I have complete respect and admiration for. He said that a couple of times he heard his infant child around the age of yours laughing and seemingly to talk to someone in her room. He walked in and she would be talking and carrying on as if someone was there. He too felt like an angel was with her. This man is highly intelligent and not a wimsy kind of guy. He believed it to his core that his daughter had an angel 'friend'.
Enjoy your little one dear!
I have heard this a few times even here on Med Help I believe we have another thread on this forum similar..I do think its possible I certainly feel in their innocence young children are more aware and do see things we cant see. Make some notes on where she looks and times she says the name ,its a record ,I also have heard its only babies and that as they get older the awareness disappears . Aren't they wonderful 'babies and Angels '..