Greetings Brian,
I, as well as my colleagues in horticulture, have received a lot of these kind of calls this spring. Fortunately for you, your pin oak should fair nicely in the upcoming weeks.
Trees have battled weather-related phenomena for thousands of years and unless your tree's health and vigor was suspect prior to this frost, I wouldn't worry too much about it. Our oak trees down here in central Illinois broke bud several weeks ago and are now slowing emerging with tender new foliage.
Your tree should bounce back just fine - just give it some extra TLC this growing season, i.e., water and appropriate fertilizer! Make sure your soil pH is suitable for growing a healthy, vigorous pin oak - these trees like acid soils. Iron chelate or sulfur amendments to the soil may be necessary.
