She was a CCP member but easily meets the exemption requirements, since she only was pushed into it in college for "job opportunities" (which she never took advantage of) and hasn't been a member or paid dues in 15 years. That shouldn't pose any problems with the N400 but you never know whether the IO is aware of USCIS's own policies. For our AOS interview the attorney dug up and brought a massive stack of court rulings related to CCP issues but the issue was never brought up. My wife did however submit a "letter of explanation" with the I485 packet per the attorney's suggestion.
I'm not too worried about it but like @Mike E said in another thread, having a third person as a witness is invaluable in case it ever comes down to a "our word versus yours" situation. And according to her 20+ years of experience, USCIS IO's generally behave better when there is an attorney in the room - not that abusive behavior is particularly common, but it's especially uncommon when an applicant has legal representation present.