if they begin to dimple or cave in, add a little water by light spraying with warm water, make sure its warm and not cold coz cold can shock the eggs, Be careful not to add too much or get water directly on the eggs...thats wat i read on some egg care... how true it is i donot know.
i also read if they dimple it means they are drying out so the humidity needs increasing, or if they are swollen and solid to the touch, you really need to lower the humidity.
look at this it may help..scroll halfway down till u get to care for the eggs and babys.
dansweirdweb_snakes_breeding