I personally don't have a pump as of yet though in the works of hopefully gettig one as I live with full body CRPS. From all the research i have done yes the pump can cause this and is more than likely the medication and not the pump itself honestly though possible. It may be just as the other lady mentioned that it was put in wrong as it is a tricky procdure getting the catheter in the right place mainly. However most of the time those who get a pump have to have the medications adjusted for up to a year before getting them set right for them as far as the right med and correct dosage to kill the pain but not using anymore medication than needed. There is also an issue with the pump where granuloma's can form at the tip of the catheter as well and this can be an issue but don't think it is what is causing what your explaining as most times this is noticed by witdrawls from the meds due to the cath being blocked and the meds not making it to where they need to go into the epdural space or spinal fluid which ever the meds are directed to for you. Anyway this is my thoughts on your question based soely on my research done and the many others who suffer with chronic pain whom have the pump that I have talked with and I hope it helps. One thing is for sure you need to contact your Pain Dr and let him know of the issue and have it looked into.
God Bless, Jeff