I have had the same issue myself. I heavily muscled person will often have an elevated creatinine level as it is a byproduct of muscle breakdown. My doctor recommended that I take a couple of days off from training and drink plenty of water. My level came back down to where it usually is, which is always a bit elevated.
training with weights are extremely strenous activity and causes all sorts of body chemistry changes. you'll get more accurate bloodwork if you took a week or 2 off from training.