Transferring wav to another DAW: Audio becomes "squashed" (2x speed, 1/2 length)

I've recorded some audio to send to my friend to use in his mix. However, when I send him the file and he places it in his DAW (mine is Reaper, his is Ableton), the file time goes from 5 minutes to almost half of that, with everything playing faster. I figured it must be to do with a difference in my rendering settings and his project settings, but we've looked into it and it seems that his project settings are 24 bit, 44100 sample rate, and my render settings are the same. I'm sending it as a WAV, and we're both on 64 bit windows. Anyone any idea what could be causing this?

[edit] Solved: Thanks guys, turns out he simply hadn't disabled auto-warping as you said. Sorry I couldn't provide more info as it was on his end and I couldn't see what he was doing / what the problem was.