I can't really say you should be concerned, since I know of some who've done the same thing.
The cable between the PI29 R1 and SWM1\PWR port of the SWM8 is less the a foot. Another 1 foot cable from the PI29 runs to a 4 way splitter.
I am not experiencing any issues should I be concerned?
The min distance came from DirecTV, and it would seem they found "some cases" where there were problems.
It does sound like you have a splitter very close, so swapping the location of the PI and the splitter, so it's SWM8 ->1' coax-> 4-way -> 1' coax -> PI [on the power passing port]-> receiver, wouldn't be hard to do.