Cubase export audio file size problem

Hello, any advice on this appreciated: I usually use the “export audio” function to save a project as an audio file - normally an AIFF file of 2 or 3 minutes results in a file size of 40 - 60 -ish MB - however I’ve got a project on the go at the moment, nothing out of the ordinary, just 7 or 8 audio tracks, about 2 minutes total - the export audio is taking a long time and the resulting file is showing at 3.2GB! I’m totally baffled as to why this is happening, any ideas? Thank you.