The reasoning behind that logic is this: if a is true, then a == true returns true. If a is false then a == true returns false. So... basically it's just redundant. Doesn't hurt if you explicitly make the comparison, though, so honestly don't bother much about it.
EDIT: also if somebody ever tells you that the comparison makes the program slower, tell them the compiler is smart enough to optimize it. I hope you don't meet such a person, but that could happen.