Not with apples but with peaches and plums. Luckily fruit trees produce way more blooms than they can grow fruit. Not all of the blooms, in all likely hood, have bloomed, and a light frost will do nothing except thin the fruit for you. It all depends on how long it is below 32F. If only for a short period you probably won't know the difference. Blooms can withstand temps below freezing down to about 25F-27F for short periods. What is really affected by 32F temps are the tiny fruit that have just set and 32F will kill them.