My thoughts are your shot wasn't a good of a placement as you had hoped, and deer are amazingly tough animals with a strong will to live? Think that bullet/powder combination is plenty of oomph to do the job.
Agree. My guess is the blood was more dark red than foamy pink. You can still put a bullet through the rib cage without completely collapsing the lungs. The shot was a bit too high. Could have clipped some lung, but even a smoker can run a long way on 3/4 lung capacity.I'm not sure but even if the bullet did not expand, I don't see a deer with a 1/2" hole thru both lungs going 2 miles.