Following up on Possible Sign of Life on Venus. After that announcement some scientists took another look at 1978 data from the Pioneer Venus Multiprobe. At the time nobody was specifically looking for phosphine, but a new analysis of the raw data supports the possibility that there is phospine in the atmosphere of Venus. Details at Is Phosphine in the Mass Spectra from Venus’ Clouds?.
This has happened before in astronomy. After both Neptune and Pluto were discovered, astronomers looked at old records and found that their predecessors had seen both bodies, but had not realized they were significant. In the case of Neptune one of those predecessors was Galileo.