From what I understand the US saw and announced the launch but the Saudis protective batteries were protecting the refinery from Yemen sourced attacks. So although warned couldn't use the assets. Iran also used Kuwaiti airspace illegally and knew the holes in Saudi airspace. Which raises the question why would they have holes in their air defense in the direction of Iran?
What I heard is going on right now with the Saudis is they are redeploying assets, covering the airspace holes, purchasing new equipment, looking at retaliation options and putting together an alliance. It only makes sense the Saudis will have to react towards improving their defenses before retaliation. Most military people I've heard have all expressed the Saudi's are forced to respond because not responding will only result in more attacks.
The Iranians have stated any attack on their soil will result in war. So folks its probable this is escalating into a war.
Evidently in slow motion.