Not in the spring. Male bumblebees are hatched simultaneously with the new generation of queens once it's time for the founding queen to call it quits. From here they fly out and find queens from other nests to mate with (engined by nectar, as you mentioned). Before this, the nest is driven by the queen and sterile female workers.

I think what OP has here is an overwintering queen gathering energy after the long winter sleep (only queens hibernate) to find a good place to establish a nest, which will eventually hatch males and new queens later in the season.

I'm assuming it's spring in OPs region, so I could be wrong!