"Mama, I scared!"

My almost 2 y.o. DS has, for the past couple of weeks, taken to telling me, "Mama, I scared!" All the time. Sometimes it's when he hears a noise. Sometimes its kind of random.

Like this morning we were driving and there was a white pick up truck in front of us. He said, "truck" and I said, "what color is the truck?" "Orange." (He says everything is orange!). When we got home, about 10 minutes later, and pulled into the parking garage, he said, "Mama, I scared!" I asked him what he was scared of and he said, "Truck." There was no truck in sight, so I asked him what truck and he said "Orange truck." He hadn't seemed scared at all when we first saw the truck, or afterwards.

Often when he says he's scared he doesn't even seem scared -- he just wants to be held or is just saying it for fun.

Does this sound like normal toddler behavior? How would you respond? Right now I usually just say something like, "Oh, you'r scared of the truck? Did it make a loud noise?" But this feels kind of inadequate. Also the frequency of his being scared seems a bit extreme and worrisome to me.