Then he did not clean the floor right - generally takes three cleaning after grouting and BEFORE sealing - one gross cleaning, usually done with wet sponge after grout has set but before it totally dries, which takes off the residual grout on the surface of the tile. Then after the grout has set (usually next day), a thorough wet mop or sponge (FREQUENTLY rinsed out) cleaning, followed (usually immediately) by a clean (new) sponge cleaning with cold water and rinsing out in a bucket of water EVERY swipe.
If he left haze on the tile and sealed, the sealer will not bond as well to the grout (and tile if a porous tile that gets sealed). Whether he will get the haze off now that it is sealed is questionable - but he should elbow-grease off the haze (including at the grout joints), then reseal the joints (and tile if type that gets sealed - i.e. pretty much anything but glazed ceramic tile or fused porcelain tile.
And yes - new floor should be left in spotless condition - countertops and counters and such wiped down with clean damp rag, floor sponge cleaned totally clean before sealing, and blocked off to walking till sealer is cured.
