Yes it could be your appendix. Some surgerical Drs usually will remove the appendix while they are doing your current surgery, and of coarse others don't. You need to contact your surgeon to see if he did remove it and if not you need to see him asap because it could have something to do with your surgery. This is nothing to fool around with because if it is your appendix it could burst and then you will be in big trouble. Being that I don't know what he did inside its really hard to pinpoint exactly what was done inside.