If the video is now at 29.97fps you should use Cinema Tools to conform it to 23.98fps. If you don’t see any interlace artifacts, then you can be sure that both fields are infact representing a progressive frame, and you’re fine. Progressive video is “embedded” into interlaced video like this quite frequently, and when it’s in the computer, it’s treated as progressive and looks progressive.
Graeme
– http://www.nattress.com – Film Effects and Standards Conversion for FCP