It can, especially if you add buffers to your tap water. If your tap water is from a municipal source, they can add different chemicals to the water before it reaches you. If you have not been doing regular water changes and you change a large portion of water it could.
Everyones water is different, and so it is really trial and error and if you suspect that you are getting a large pH swing, then you have to do some homework and figure out where exactly the issue is. Also keep in mind, that it is better not to manipulate your water conditions, it is this up and down that can stress your fish. A more stable pH is better even if it is not the ideal pH for the cichlids you are keeping. You always want to be careful if you are playing around with your pH.