Wow,what a valentines present.I just got a card.

If she really loved you she would have gotten you a Hoyt.
I believe it is a timing issue and would have your local shop look at it.I would bet that the cable needs to be twisted up.And yes,even a 1 cam will have timing issues.The cam must be rotated properly to perform at it' s optimum.
The Zebra string should be sufficient but is far from being one of the best.IMO.