Not saying this is what happened here, but I sometimes check out people in PA28s who turn the fuel pump off at 300 feet ie the time you need that redundancy the most, because "that's what my instructor told me to do" rather than read the POH or even consider what the electric pump is there for.
If the engine driven pump fails it will take about 1000 feet of gliding after turning the electric pump on before the engine will have fuel again.
Some of the really old PA28s don't have the safety catch to stop you turning it off by mistake. The 151 does.
Glad they are OK! Good job.