Any meeting where a quorum of members of a public body is present is subject to the Open Meetings Act if public business is being discussed or formal action is being taken. NMSA 1978 § 10-15-1-B

A public meeting may occur even if a quorum of the members are not in the same location. For example, a city manager who talks individually to a quorum of the members to determine their position about a proposal would violate OMA. This is known as a rolling quorum. Public officials texting one another during a meeting also risk an OMA violation for creating a rolling quorum. (AG OMA Guide 2015 Commentary)  p. 7