You sure about that Lucy? Last time I checked (which was when I put in my packet), if you attend graduate school then your Graduate GPA is separate than that of your Undergraduate GPA. It DOES matter even if you haven't received your master's degree (at the time, I hadn't either) and THEY ARE TWO separate GPA's...the grades from your undergraduate degree/classes and graduate degrees/classes are never added and cumulatively averaged.
He will have an undergraduate GPA (cumulative and major GPA), and he will have a graduate GPA (cumulative only since graduate degrees are geared to a specific focus - i.e. you don't have to take liberal arts class for elective towards your Biology graduate degree, you only take biology related courses).
And it is a big deal even if he never gets his degree in a graduate program. But most people get a more boastful graduate GPA for the reason stated earlier - you don't have to take boring, unrelated classes and you are there for a specific focus and desire....so ultimately, since you are interested in the topic and class, you perform better and get higher grades.
Good news is that if on the first page, it asks for GPA (and only room for one), he CAN and SHOULD put his most CURRENT GPA - which, if he is taking graduate courses and has only completed one class and received an "A" - then, poof, he has a current GPA of 4.0. His transcripts will reflect his undergraduate degree obtained and his major and cumulative GPA that he received on that degree and his graduate transcripts will reflect his current graduate GPA and degree plan.
But never, to my knowledge, are the two ever combined in calculations.