Vincent,
My research, below, shows that NY has a one-party consent law for recordings. This means that as long as one person in the meeting is informed and consents to the recording then it is legal.
Link to site:
Citizens Media web site showing NY recording laws with links to other states.
Even though it is legal, I personally believe that everyone in the meeting should be informed. As you said, failure to inform everyone (even if you don't require everyone's consent), creates trust issues.
I would suggest you start asking at the beginning of every meeting if the meeting is being taped. Additionally, the Board may adopt rules that prohibit recordings or require that everyone involved is informed prior to the recording.
Hope this helps.
Tim