The thing i advocate is, so long as your gear is under warranty, both body and lens WR that is, use it as per normal and make it a habit to literally hose/wash/spray it down every single day.
Anytime there's a problem, just send the kit back for repairs. And don't be so detailed in what you did, just say you were caught in light rain and the leakage happened.
*It don't matter if DA lenses have slightly lesser sealings or not.. If Pentax lies, so can you...
*
On top of ensuring that your kit is clean, just like your clothes, this also helps the Pentax community as a whole to provide a physical feedback to Pentax HQ of it's QC.
Best to discover and keep sending it back for repair/exchange until it's confirmed that your kit has no issues whatsoever, before the day comes when you are caught in the rain and out of warranty.. Then woops! You only have yourself to blame..