DCP Massive file size predicted, what gives?

Hi all

I have made a DCP successfully of a 1h 17min film. Prores sequence, 1080p, 5.1.

Adobe Premiere 8.1 CC. Updated.

Last one I made in November (also 8.1) turned out around 45GB as a finished DCP Package.

I have just made a new sequence with a couple of changes, and when I cue it up to export the predicted filesize is almost 1TB.

I cannot see anything obvious, what gives?