I just finished developing some negatives, and I noticed something interesting.

Of five negatives developed in a Jobo Expert in Rollo Pyro, two came out with highlights that seemed a little thin. All of the negatives were exposed at the same time, in controlled light, and of course developed at the same time for the same time, temp, rotation, etc. because they were all together in the Jobo.

How can this be? How can two negatives have thinner highlights, and the other five seem perfect? They're all printable, just seem to be developed differently.

HP5 film, if it matters.