First of all, we don't know whether they were lying. Second of all, if they were, they may have been forced by the government to lie. The FISA requests they were getting also came with gag orders.
I have not read the law, but I think a gag order can't force you to lie. Lie to a directly asked question, gray area; issue a lying press release or blog post, not mandatory.
I am not a lawyer.