Negative timestamps of beats  #3

Occasionally, I get negative timestamps of the corrected taps at the beginning of the audio.

To reproduce, if you try with
https://github.com/urinieto/harmonixset/blob/master/dataset/beats_and_downbeats/0440_loveyoulikealovesong.txt which starts like that

0.06071433125,1
0.571429,2
1.08425,3
1.597071,4
2.109892,1
2.622713,2

and its corresponding youtube video http://www.youtube.com/watch?v=EgT_us6AsDg
the audio is misaligned to the taps.

After the correction, the output start with:

-0.93928566875,"1"
-0.42857100000000004,"2"
0.08424999999999994,"3"
0.5970709999999999,"4"
1.1098919999999999,"1"
1.622713,"2"

Obviously madmom thinks the downbeats start on different phase than the tapped ones, and thus the beat 1 is on negative.