What the heck was that?

I think this is a goldfinch, one morning while I was getting the coffee ready I heard this kind of loud, pretty but odd whistling sound. It was coming from this bird and it's partner whose picture I didn't get. They were hanging out in my young white cedar trees. I haven't seen them since, guess my yard doesn't agree with them! It was fun to watch them flit around and play, all the while making that distinctive chirping.