Wildlife Spotting

This little bird was just sitting by the door at my office one morning. I was so fascinated but it did not fly away and I had to get closer to get a photo. I don't know if this little bird had flown into a window at work or if it was sleeping. After I went back out later to check on it it was gone. I thought I had identified this as a northern Parula Warbler but I am not sure if that is correct.