When this card is Normal Summoned: You can Special Summon 1 Level 4 or lower monster from your hand, also, after that, change this card to Defense Position.
So if Goblindbergh was flip summoned, its effect will activate?
A flip summon does not count as a normal summon. For this effect to activate you would have to summon it from your hand in face up attack position (a normal summon as stated).
It is not specifically stated in the rules as such but the implications are made by statements mentioning flip summoning as many times as you want and that a flip summon does not take up a normal summon.