I agree it is unlikely to be reticulation, within 4-5 deg F, but I suggest you get all the fluid (dev, stop, fix, wash) to the same temperature (within 1 deg F) just in case. Leaving the chemicals and a bucket of water overnight in a room at that temperature should do the trick.(posted 9007 days ago)Overused fixer causes underfixed negatives, which is far worse than mere reticulation. Some peopled in this forum have said that hardener in the fixer will reduce the chances of reticulation.
Genuine grain is proportional to developing time, and if the results are better with less development, then that is what it is. You might prefer a finer grain developer, such as Microphen. Or a finer grain film, such as Pan F+, or Delta 100 or T-Max 100.
Grain is more noticable on areas with no detail, such as out-of-focus areas. So another 'cure' is to ensure your pictures contain no out-of- focus areas.