Another is that it is being handled through OTC which doesn't always show all the trades.
I wouldn't take it as a negative or positive. Just markets like the OTC can be illiquid and small, and therefore not as transparent. However it gives American investors the opportunity to transact in Canadian stocks like Novo on the US side.
I would go off the transactions that run through the TSX. You can view them at http://tmx.quotemedia.com/quote.php?qm_symbol=NVO:CNX. It's very basic.. can only see the nearest bid/ask with last 10 transactions but better to start here than go off of the OTC price.