February 29, 2012?
Under the old residency requirement rules, February 29 in a leap year did not count (not as a day present, if in Canada on that date, and not as a day absent if outside Canada on that date). Residency was based on years.
Under the new physical presence requirements, the requirements are specified in terms of days, so all days count, and indeed all days any part of which was spent in Canada counts (so under new rules, both the date of exit and date of entry count as a day in Canada; under old system, credit was for one or the other, not both).
Yes, under the old rules confusion was common, since the requirement was to be "resident in Canada" for three years, but the manner of calculating residency referenced days (allowing half-day credits for time living in Canada prior to becoming a PR). There were other less than precise elements in the old requirements, many often causing confusion and leading to a great deal of litigation over the years, and indeed Federal Court justices had been railing about the need to change the law, to adopt a more precise residency requirement, for more than a quarter century before it finally did get changed.