In Section 4 of the women’s 1500 at Saturday’s Occidental Invitational in Los Angeles, Aeron Arlin Genet of California’s Central Coast ran 4:54.74. Not that impressive until you know she turned 50 last June. That puts her 3 seconds behind the listed American age-group record of 4:51.86 by Marisa Sutera Strange in 2015. With the season still young, Aeron could snag the AR yet. (The W50 WR is a stretch, though — 4:36.79 by Britain’s Clare Elms in 2014.) According to mastersrankings.com, the best 50-plus woman in the world this year is Sally Gibbs of New Zealand, who clocked 4:48.49…