Ask Mr. Smarty Plants

Quercus hemisphaerica (Darlington oak)  (also known as a Laurel Oak) is shown in this USDA Plant Profile as growing in some counties on the Texas coast, not necessarily in Harris County, but close, in USDA Hardiness Zone 9a. The person who wrote this Floridata article on Laurel Oak is obviously not too fond of it. From that article:

"Laurel oak is tardily deciduous, meaning it drops a few of its old leaves during the winter, but sheds most of them all at once as the new leaves unfurl and flowering begins in early spring."

This indicates to us that your tree should now have some leaves and  blooms on it, because oaks sure are blooming (and driving everyone crazy) here. Try the thumbnail test: scrape a very thin layer of bark off an upper branch, and work down doing the same thing going down the tree. If there is a thin lining of green under the bark, there is still hope. If there is any other color, the tree is done for. 

A 25 ft. oak is a pretty big tree to be transplanting, and if it is not showing signs of life, we might blame it on that. Was it planted by you or the nursery from which you purchased it or an arborist? From Helium.com Tips for Transplanting Oak Trees:

"Transplanting an oak is a labor-intensive task. Oaks are most easily transplanted when they are small (under three feet tall) and less than three years old. Oaks develop a taproot that often can be almost as long as the tree is tall. Cutting the taproot usually results in the tree dying within months after it is planted. For this reason substantial digging is required so the whole tree (taproot and the root mass) can be removed from the hole."

From Duke University, here are some pictures of the leaves and bark of this tree. There seems to be some confusion on exactly what tree the Laurel Oak is; read this article from the University of Florida Extension on Laurel Oak or Swamp Laurel Oak? Nursery retailers sometimes take some liberties with common names, and the one you have might not even grow well in your area. 

So, to get down to your question: Should it go back to the nursery? Well, first, do you have a warranty from the nursery? If you do, and it has to show signs of growth within a certain amount of time, you should definitely go in and talk to whoever sold it to you. As to whether it had suffered because of the freezes we had during the Winter; certainly if the tree was in an exposed location, rooted in a plastic can, and the temperatures got pretty cold, it could well damage the roots. We all had some unusual weather this year, but it's not a given that the temperatures ever got cold enough in South Texas to do damage. Even so, we would recommend that you go back in to the retailer, look at any Laurel Oaks that they have in stock, and see what they look like. 

Finally, we really can't say why your tree has not leafed out. We feel the top candidate for the problems is the transplanting of a tree that is too big to survive it. 

Pictures of Quercus hemisphaerica (Darlington oak) from Google.