I got it home and promptly cracked the worktop while assembling it.
If it cracked while you were simply setting the top panel onto the legs, it's definitely a defect (and most likely the crack was already there when you bought it but not visible). We routinely stand our doubles on the edge and sit while wearing all our gear on the edges and corners; in general I've never been "careful" or gingerly with mine; just not abusive. I've had mine for several years and I'm still on my first table.