Definitely not normal. In order to determine the problem, you should carefully measure and record certain critical distances like brace height, ATA, nock distance from cam, peep location (if you use one), cam position, and tiller. This has to be done when the bow is in perfect tune and shooting broadheads exactly as it should. Then, it's easy to figure out if anything has moved and what has to be done to correct it.

bow hunter44, "creep" is the permanent elongation of the string. "Stretch" is lengthening that returns to normal (like a rubber band). All strings have at least a small amount of stretch to them. It is not something to worry about. Creep on the other hand, is very bad. If it happens, your bow is no longer in tune. Changing a sight position will not correct the problem.