In my experience with Samantha's treatments it absolutely looks darker/more red for a few weeks afterwards. I will give you an example...
Sam had her last laser treatment on Sept. 14. Her first birthday party was on Ocober 14th and, unfortunately, we had some issues with her health that week so we were very preoccupied. When things finally settled down we had our family at our house one day and everyone was commenting how light her birthmark looked. We had been so worried about other things that we never even noticed until then. It was such a huge difference!
I totally agree that you should at least give it a few more weeks before you become concerned at all.