Of course it's true. Most of congress doesn't even have security clearance to know what exactly the NSA is doing, and the ones that do technically have the clearance can really only questions things they are already aware of - there is no onus on the NSA to report anything themselves. Just look at the response by congress and the whitehouse to the Snowden leaks - they all claimed to be completely unaware of what was going on. If you actually read Snowden's book and leaks you will see very clearly that the NSA can launch a program that is classified from congress, that they literally do not need to report on to anyone including the president.