snip
...and my FSDs were deep charge G5 engineered for range. Maybe engineering had something to do with it?
On a sidenote...
Better don't go for deep charge as special effect, as it has no real benefits and reduces the overall range of your ship and it's only viable for ships below (around) 250t hull mass.
Above that border you're getting always a better jumprange with mass manager and of course a better overall range because of less fuel consumption.
The difference in jumprange between MM and DC below 250t hull mass is more or less marginal, like 38.10 ly (MM) to 38.14 ly (DC) on a stock Cobra Mk III with just a 4A FSD (ref. to Coriolis.io), but the overall jumprange gets reduced from 209,09 ly to 183.50 ly.
On topic: it seems to happen when you fly near, or better said, through the very last, barely noticeable outskirts of a white dwarfs jet cone and your scoop sniffs away only the smallest particles and your ship's voice gets mad on that. Sometimes really annoying...