I think many things can cause a change in bg levels using a pump. Sometimes its due to a change in hormones, sometimes the weather temp, sometimes having a set in an area on the body where for some reason or another insulin is not being absorbed wonderfully well and sometimes weight gain.
Usually if you find that you are needing to do a lot of corrections and its an ongoing thing, then you should look at the times the change in bg levels happen and do a basal test again. The same goes for low bg levels as well.
Having a pump keeps everyone on their toes so try not to worry and just sort out your insulin needs again.