It’s something I have never noticed before. While the hours of daylight get longer after the winter solstice the time of the actual sunrise gets later. The sunrise for our area on December 21st was 7:47:16 am and the sunrise on January 4th was 7:49:34 am. I realize it isn’t that big of a difference but it just sounded strange. I also thought the earliest sunset for us would be on the solstice but that isn’t the case either. According to the Sunrise/Sunset Calendar the earliest sunset was at 4:09:14 pm on December 10th and on the solstice sunset was at 4:12:15 pm. The sun will start rising earlier again but for a few days it keeps us wondering.
You can read more about the specifics here.