If I had any doubts about the land agent I would call EOG’s land department in Houston and verify if the land agent is authorized by EOG to negotiate mineral leases. Also on the Mineral Lease Form itself it should specify the name of the Operator, in this case EOG, as the entity primarily responsible for drilling operations. I would not be concerned about a land agent utilizing a cell phone or a non-Company e-mail address. This is more often the rule instead of the exception in my past experiences.