Any ideas on what I might be doing wrong?

After I receive my order, I always put my cigars in my humidor for a few weeks before smoking any. After this time period, the flavours are very deep and rich, but after I let them sit in my humidor for a few months or so, and I go back to smoke one, the flavours are no where near as intense as they were just a few weeks off of the truck. What could be wrong? Is this indicative of a humidor that is too dry? Too humid? Too much change from one day to the next as to temperature/humidity?
What could I be doing wrong?