Umm...actually no they're not fine, especially for animals so small and sensitive to thermal heat burns like those babies. Do you have a digital heat probe? Put it on the rock and see how hot it gets. Anything over 90 is too hot. Heat rocks are bad and old school. No respectable herp keeper uses them, they are old obsolete technology. They don't have a thermostat so you can't adjust how hot they get. They can and will burn animals. Please get an under the tank heater.
have you read about under the tank heaters, they are worse than just putting an uncontrolled heat rock in there. by touching bothwhile heated the UTH is hotter than the heatrock, which is over 3yrs. old. the voltage from the heatrock is less way than the under the tank heater. Just because you have read an article on not having them doesn't mean I cannot, I never ever asked for an opinion about the geckos or their habitat, I just posted that I had them, period! I need no advice and when I do I will ask somewhere else where the advice givers give real advice from real sources instead of a site where everyone thinks they know what they are talking about! You have geckos to sell their babies, I have them to love and take care of!