We've investigated some reported cases of post-release issues with tradelist counts, and the confusion lies with the following scenario:
A user could have had 4 Arid mesa in his inventory, with details on all 4 and marked all of them in the details panel as For Trade. Initially the tradelist count would be 4 for them, so all was ok.
If later the user changed the 4 tradelist count to 0, they would stop showing in his tradelist, but in the details panel, all 4 of them would still be marked as tradeable unless you manually unchecked them too. (This of course was a problem / bug with the old system)

When we migrated to the new release, in these conflicting cases we gave priority to what users have specified in the details panel. So if you had the 4 zendikar fetches marked as for trade in the details panel, now you have a 4 in the trade count.
Hopefully that explanation makes sense. The conclusion is that these cases were already conflicting and inconsistent, but the user did not see that though a bug in the old system. We could not ignore what the user set in the details panel either, for technical reasons we cannot go into in such a short post as this
.
We have reason to believe these situations were very rare though, so not many people should be affected by this. Sorry for the inconveniences caused.