Simply put, my space platform received a delivery from a rocket silo while in-motion between planets. I think it occurred because I manually sent up the rocket just as the platform's wait condition was fulfilled (ftr, was "0 Agricultural science packs" and "wait 60 seconds", the former was met and the latter was counting down). The rocket launched normally and the platform set off to Gleba, confusing me, and I watched it to make sure the rocket delivery was received, and it was.
