Our pupils are controlled by the tiny muscle of our pupils, and if anything strange happens, such as horrifying occasions, panick or surprise, our brain would simply dictate our pupils to be dilated and that is quite natural and temporarily. Take it easy, nothing serious unless it is not resulted from drug use.
Well, yes, when you are excited, you will be possible to have dilated pupils. As we know that when you are excited, your blood pressure will be high. In that way, it will affect your eyes, leading to dilated pupils, for high blood pressure is the most common cause of dilated pupils. On the other hand, drug use, illness, and trauma can cause it too. So just pay more attention to it. And control your own emotion.
Yes, you will get the dilated eyes when you get excited. When you are in the excited state, your blood pressure will increase and your eye nerves will be intense too. The pupils will be dilated in the unconscious state. You may find that they will be released by themselves after a while. After you calm down a little, the dilated eyes will disappear.