that sounds weird - just keep an eye on him. if you have gravel, wood chips, or anything swallow-able get it out of the tank. use coconut fiber bedding instead (like 'bed-a-beast' and 'eco-earth/ brand bricks of bedding).
I never understand how there is such a difference in gallons for whites. Most people either say 10 or 20 gallon for a white. Then again who knows really? Everyone gets their information from SOMEWHERE and so which refrence is correct. How do we know?