It wouldn't surprise me if it was something similar as to what I saw on skyscanner, I asked them what was going on and they replied the following:
The prices we show on Skyscanner for KLM are supplied by their systems. On Sunday, we found a problem with the prices they were supplying, which didn’t include a mandatory fuel surcharge. As soon as we realised this issue, we removed their prices from Skyscanner until this could be fixed to try and minimise the impact on our users. Unfortunately, it seems that you were one of a number of users who saw the incorrect prices before we were able to remove them.
If it ain't Dutch, it ain't much.