Making up formula

I've always made up my son's formula using the nuby rapid cool, if we're at home I use boiling water straight from the kettle into the rapid cool with the milk powder. If we're going out I put the boiling water from the kettle straight into the flask were taking out with us. I've never waited for the kettle to cool down before using the water to make the formula. Is this wrong?! I read online that you should leave the kettle to cool before using the water and now I'm panicking. My son is 10 months old, we've always done it this way and had no problems but now I'm worried I could be affecting the formula in some way by making it up with freshly boiled water?! Advise pls lol