Forgot coolant cap

2007 Volvo D12 with 2 million kms. I did a trip of 550 miles. When i was doing a pre tip inspection the next day, I saw there was no coolant cap and my heart sank. Most likely, when I topped the coolant before the trip, i forgot to put the coolant cap back on. Truck was driven in -10 Celsius temperatures and it did not overheat at all. The oil temperature stayed near the 180 mark all the time. Coolant was also above the minimum mark after the trip. I am worried that I might have damaged something. What do you guys think?

 

Do i need to drain my coolant and refill just in case air might have gotten in? I checked the dip stick, it has oil. There were no signs of overheating as the temp gauge stayed in normal operating zone. I bought a new cap. I did a trip with the new cap on, I opened the cap and i saw small amount of water inside the cap. I didn’t use to see it in the older cap. Although, the cap that I got is a new Doorman cap and the older cap that got lost was a little different. It didn’t have a tip on top of it, it was flat. I did get the new cap from volvo dealer.

 

Do i need to drain and refill coolant? I did 2 trips with the new cap on. After the first trip, i saw very small amount of water inside the cap. Before the second trip, after i had left the truck off overnight, I opened the cap and saw a very small amount of ice inside the cap. I think the water that was stuck to the cap froze overnight. Could it be a faulty new cap? I did get it from a volvo dealer but it is not the same as my old cap