Yeah thats about right. Basking surfaces should generally be between about 100-110 with areas around that in the 90s and a gradient down to 75-85 or so during the day. You are providing a good gradient so as long as you are getting accurate surface temps that should be OK. You can adjust based on your dragon's reaction/behavior. A lot of time basking you can try increasing temps a bit. If he avoids being directly under the basking light, you can decrease it a bit, etc. They tend to have their own preferences so the ranges are a good common starting point.