Podcast issue!

I have been following c25k and noticed with the last couple of runs that the timing is way out! Not sure if it is the podcast or my iPod at fault! So, when Laura is telling me I have completed a 5 min run, it isn't actually 5 mins so I finish the W4 run/walk sequence in 18 mins when it should take about 21! Anyone else had this problem? The music does seem very fast at times!