Nah, we were just lucky. If the sky was overcast, there would have been nothing interesting to shoot. As a landscape photographer, usually you'd go back to shoot the same scene over and over under different weather conditions just to capture the best one.
You were with the morning outing as well. For me, I've been to the Esplanade more than 10 times, on my own and with outings, just to capture the CBD skyline, with different lenses.
I find the best morning blue shot, is just after it rains. The air is crispier, and less dirty. Just my opinion.
So, after this outing, hope it gives you the encouragement to go out and shoot such scenes on your own.
HTH.
About the above picture, watch the horizon level, as it is tilted downwards to the left.
Cheers!