It has been my experience with batter based quick breads (waffles, pancakes, etc) that yes, they very often tighten up/thicken after 30 minutes or so.

thanks alot for the answer "The Lard of Avon", it did thicken-up after 30 mins. The Pancake recipe that i often use, can be pour straight away after been mixed.

anyhow, do you think i could put the batter (especially this one, since it has cornstarch in it)

I'm not sure what you mean by "put the batter".

put the batter on the fridge, i forgot to put a word there

I have made the batter the night before and fridged it. Cooked in the morning it was great.

You could definitely chill the batter & use it at a later time, but my only concern would be that chemical based leavening (IE baking powder & soda) is best when it's freshest. Unlike yeast, which is alive & feeding off various sugars and therefore adds more leavening over time, the CO2 being created by the interaction of these leavening agents is best when it's freshest. That said, homemade waffles, even if not at their best, are still yummy :)