One crop, one country, and officially only for one year, 9 years ago - and yet there is contamination. On 8 September 2009, German authorities notified the other EU member states that they had found unathorized GM flax (linseed) in a shipment from Canada via Belgium (RASFF 2009.1171). The flax (FP967/CDC, Triffid) is herbicide-tolerant, but to a different class of herbicides then usually used with GM crops, and it carries an antibiotic resistance gene as marker.

The GM contamination register reports that the flax was approved for cultivation in Canada in 1998, and it was cultivated only in 2000. Wishing to protect their export markets to Europe, the Flax Council of Canada and the Saskatchewan Flax Development Commission convinced the Canadian Food Inspection Agency to remove variety registration for the GM flax in 2001, making it illegal to grow. In 2001 about 40 farmers were multiplying 200,000 bushels of seed for future use but this was all crushed when the flax was taken off the market that year.
German authorities found the contamination in 16 out of 41 samples of cereals and bakery products containing conventional flax. Organic products were not affected. In the days following the discovery Greenpeace Germany took additional samples from and still found GM contamination in a large proportion of them. Strangely enough - while the Germany authorities had notified the EU authorities about the contamination in cereals, bakery products and nut products, no such notification has come from any other member state.
Canada is the world leader of production and export of flax. Even before the contamination was confirmed the Canadian flax prices dropped by more then 30%: yet another case proofing that contamination is not just a problem to individual farmer, but that it damages the whole branche. After US rice exports and prices dropped dramatically after LL601 rice contamination was found in 2006, Bayer had to pay damage compensation even to farmers who did not have contaminated harvests themselves.
Apparently the contamination was found in a random check by German authorities who apparently had not been checking for this specific GM crop, but possibly for contamination of the shipment with other GMOs. In this case it was possible to identify the GM in question quite fast - in other cases it took much longer. If anything this case show two things: (1) the risk of contamination is not over once a GM crop is not officially cultivated anymore, and (2) we need not only a database with information and reference material of GM crops approved and cultivated somewhere around the world, we also need this information on GMOs that are only grown for a few years or that never even were commericialized (like we have seen with LL601 rice). And we need national authorities that have the capacity to check harvests and imports.