My Carpet Python wont eat

Question
I have a 20 year old carpet Python that has been off feed for about 3-4 months. Is this something I should expect due to his age or should I be concerned?

Answer
I'm going to assume, since we're talking, that going off feed is NOT normal for your snake.  As such, you should be concerned.  Unless, of course you just got this snake, and he winter cycling and this is just the first time you've seen it.  Which is the case?