Slightly longer answer: probably not
Even longer answer: While the evidence is largely anecdotal, Apple has certainly modified the iPhone design. These modifications seem to keep water out - to an extent, as found in various internet searches. Our iPhone 6SP isn't scheduled for delivery until tomorrow, so while we haven't actually seen these modifications personally, the internet has no shortage of 6S and 6SP teardowns and tests. Below is just one screenshot of a video on YouTube questioning this very subject.