Normal
Don't worry about "humidity" as humidity in the air is irrelevant to tarantulas, not to mention it is added stress. Follow what [USER=4947]@Nunua[/USER] said and you will be good to go.GBB slings do seem to like a bit more moisture in the substrate than larger specimens do. Overflowing the water dish answers most moisture answers.
Don't worry about "humidity" as humidity in the air is irrelevant to tarantulas, not to mention it is added stress. Follow what [USER=4947]@Nunua[/USER] said and you will be good to go.
GBB slings do seem to like a bit more moisture in the substrate than larger specimens do. Overflowing the water dish answers most moisture answers.