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Actually there is at least on instance of February the 30th in history:
Sweden adopted the leap-year rule of the Gregorian calendar in 1700, making it a non-leap year, but without adjusting the calendar otherwise, so that after that Sweden was out of sync with both Julian and Gregorian calendars. After a while they discovered it was not such a great idea, and in 1712 Sweden moved back to Julian calendar by adding an extra day to February, resulting in the unusual date of 30 February 1712. One should be careful in rejecting "impossible" dates...<P>Of course that date wasn't a 'palindrome' day