I consider waiting until it is less obvious to "tell off" (interpret) the symbolism. That is, in addition to being tempted to see the dream as meaningless, I am tempted (by the desire to go back to sleep) to postpone interpretation of the dream until morning, when the symbolism of the dream will be less obvious and less clearly related to the dream itself (the phone call).
Waiting until morning to write down the dream is likely to make the dreamer forget the dream entirely, and waiting until morning to interpret the dream may make the dreamer miss much of the interpretation.
After writing out the bulk of the dream, I was able to fill in certain gaps in my memory by working backwards from the portions of the interpretation which I had completed. At this point, the process of dreaming is fresh enough in your mind to make remembering the dream something of a symbolizing process and to make interpreting the dream something of a remembering process. One is still close enough to the dream state that one may easily go back and forth from symbol to latent content.
Thus, this dream strongly suggests recording and interpreting one's dreams immediately afterwards, rather than waiting until morning.