Yeah, this one's common with new mowers. It's not broken. The engine was run at the factory and some residual oil can get into the air cleaner. When you added the new oil, you probably overfilled it a bit. The white or blue smoke is the indicator of overfilling.
Check the oil level with the dipstick. If it's above the full mark, you'll need to drain some out until it's correct. The recommended oil for general use is SAE 10W-30.
If the smoke continues after correcting the oil level, it could point to another issue, but overfilling is the most likely culprit right out of the box.