In a self-governing republic, Congressmen should get no more or less deference in that regard, compared with "Joe Citizen."
The only perks that Congressmen get in that regard is freedom from arrest going to session, and for what they say in session (which is obviously not a "surveillance" issue, since statements in session are akin to making public pronouncement).
The CQ story says her prosecution was shut down by AG Gonzales, in exchange for political support of the administration's TSP.
No, they shouldn't, but if the Bush administration was taping, domesticly, an American citizen's conversations with a Congresswoman, because he was pro-Israel and a major Democrat donor, that's a very serious problem. I don't want administrations headed by either party doing that. Obviously all the facts aren't out, but they need to be. Then let the chips fall where they may.
BTW, if there was legitimate reason for a tap, and Gonzales shut it down for political reasons, that's not a good reflection on the prior administration.