Far be it from me to argue with the resident P-38 master, I'll give it a look again tonight.  It very well could have been my imagination.
Then again, my second argument still stands:  taking 2000 rounds really encourages you to stay in the air longer than you really should (for people learning the plane at the very least).  I don't know how many chances at  5+ kill sorties I've had and lost, all because I thought "I've still got a thousand rounds, I can stick it out a bit longer.............   ..............   ..........dammit."