Normally even that doesn't cause it to say you're moving -- but if you were rocking back and forth slightly it could.

However, if you park your bike like that, with the magnet right on the sensor ... that can lead to a dead transmitter battery by the next day, depending on the model.

If you want troublefree operation, it seems that there's two routes to take for your cyclocomputer -- 1) get a wired one -- even the cheap ones work great, or 2) get a high end wireless one. The lower end wireless ones tend to have issues, it would seem. And sometimes even the high end ones have issues.

GPS based units work pretty well too, but they have their own issues.