A top school official in a large eastern Iowa district is now out of a job, but no one is saying what happened. A cloud of secrecy hangs over the departure of Bettendorf High School’s 84-thousand-dollar-a-year principal. Dr. Tom Castle was put on paid leave Wednesday. Then, yesterday, he abruptly retired. School superintendent John Perdue won’t say why Castle had been suspended, only that it’s a personnel matter and students were not at risk. Castle, a 37-year educator who has been at Bettendorf the last 11 years, also won’t comment. Perdue says the three associate principals at Bettendorf’s only public high school will handle the duties of principal through the end of the school year.