My tracking status has said "Pending Customs Inspection" for the last 20 business days. It looks like my shipment was seized by the CBSA so I've been going through the paper work and phone calls to try and figure things out. All that was in my package was a mechbox shell and an inner barrel.
In the past, I've had all my stuff pass customs in less than 24 hours. But, I have no idea what's going on this time around. Your best bet is to wait a week and then call the CBSA to try to get an idea of what's going on.
They'll ask you for a customs number and then you have to play telephone tag between the people at Canada Post and the CBSA. It's tons of fun.