No, the copper base on the heatsink should be a little larger than the CPU. RMA it and get another heatsink.
I emailed Arctic Support and heres what they have to say... "Dear Sir,
the cooler doesn't need to cover the complete CPU, it is enough, if the cooler covers the centre of the CPU since the core is there and 98 % of the heat is emmited here.
Best regards / Mit freundlichen Grüßen"
i guess they know, no?