Just bought a newly constructed home and on the property is a well-established oak tree. This is my first year to care for the tree. When I bought the house in early fall, the tree was full and green. However, now that we are into the summer months, I noticed that the tree never fully bloomed. I am afraid the tree may be in shock. Am I being over-concerned, or is there a problem?

You have every right to be concerned. Generally mature oaks do not appreciate construction around their root systems. They do not like soil compaction from heavy equipment and do not like backfilling with soil. Look at the trunk as it enters the soil. If it looks like a telephone pole rather than having a trunk flare than backfilling has occurred. Unfortunately construction damage is much easier to prevent than cure. I would check with a certified arborist for suggestions once they look at it. Also chek with your local Extension office. http://aggie-horticulture.tamu.edu/extension/