This is never a good idea to record the call to discuss legal issues.
A. You have to identify you are recording the call to make it legal. If not, then it can be dismissed legally since it was not identified as being recorded. This is why you get "This call maybe recorded for Quality Assurance" Message when calling any call center. The problem is, the call may or may not be recorded.
B. Most reps are not fully trained on legal issues or even considered as a legal consult. So if you state you are recording the call, they maybe able to disconnect the call on you.
This was the process when I was in Verizon DSL/Fios. We even had a special script to cite when the end user calls in and stated they are recording the call on their end. Essentially it broke down to, "If you are calling us to discuss legal manners, then your lawyer needs to consult our legal department. Thank you and have a good day" and instantly end the call.
Even when we found out end users would call us trying to setup a web server and wanted assistance with this, we could not cite the TOS stating that a residential account cannot use web servers. We would have to send the information to another department to investigate and ban that users account for breaking the TOS.
I hated having to do this, but the double edge sword on this was if the call was recorded and I was not documented in forwarding the issue over, I would lose my job for allowing the user to break TOS.
It's my understanding that the requirement to announce you are recording the call is decided by state law but I may be incorrect. In my state we are required to announce we are recording the call so I do when I need to record a call. Obviously check your own state/federal laws before recording a call.
My position is clearly stated in previous posts in this thread, I'm simply saying that if you are going to use a rep's statement of it being ok, have it recorded for you own needs. Honestly I would expect their advise/opinions would change radically if you were recording the call, and you probably wouldn't hear these ridiculous statements that tethering without paying is OK by Verizon.
EDIT: I'm not even saying that a rep stating that it's ok will be enough to save you, but it may demonstrate that you honestly tried to determine it's legality in good faith before doing it.