Static ffmpeg and editing audio files (Ubuntu)

[richard_get_iplayer]

I have for sometime used ffmpeg (a compiled version) to edit m4a audio
files with no issues. Now, after installing ffmpeg (static version) from
Jon's ppa, I find that m4a audio files no longer edit properly. For some
reason the edited files are short in duration.

This is the code I'm using:

ffmpeg -i foo.m4a -ss hh:mm:ss -t hh:mm:ss -acodec copy output.m4a

For example:

ffmpeg -i Ed_Reardons_Week.m4a -ss 00:02:34 -t 00:27:46 -acodec copy
output.m4a

This gives a start times after 2min 34 secs and a duration of 27 min 46
secs; but the edited m4a file came out 25 min 11 secs long.

What I'm not sure is whether the problem is the static ffmpeg or some
other issue as I've just done a clean install of Ubuntu due to a failing
hard drive.

Can someone help and test whether they get the same problem.