I wouldn't worry. For one thing, concrete doesn't crack from drying out. Wood can, if it's dried too quickly, but not concrete. It is possible for a thermal shock to crack concrete, but you're 10w bulb isn't even close to being able to do that.

The only thing I might worry about would be that someone, a child particularly, might reach in and touch the bulb. It just might get hot enough to burn.

jon1270
Thanks for your reply. The lantern is in an area where it will be very unlikely a child will reach inside. It is placed off the ground on a flat rock a top of some sharp rocks. This site is a small koi pond waterfall close to the house. This light would only be on at night when my grandchildren would be inside the house. Haven't been able to try the light out yet as I was thinking of returning, I ordered this light on impulse - then had second thoughts... now need to buy the low watt transformer.
Thanks again, Wendy

I have one of those laser thermometer things and was curious, the halogens UCs we had were 400 degrees, interestingly enough this was lower then the temperature of the logs in my fireplace. So yes, I would say that the temp of the lights is dangerous and not something that I personally would touch.