When should an app proactively point out a problem it solves?

I was using the Google Fit app on my Android phone for a while to track my steps.

Later, when I got an Android Wear watch, I decided to track my steps on it rather than the phone. My watch is on me all day, not my phone. I uninstalled Fit on my phone since I had no further need for it, and because I didn't want my steps double-counted by both the watch and the phone.

But the Fit app on my watch asked me to install Fit on my paired Android phone.

I was stuck for a few days, and I eventually thought, "Screw it, if it double-counts, it double-counts, but let me try it." When I installed Fit on my phone, I discovered to my surprise that Fit on the phone works with Fit on the watch to avoid this double-counting problem.

It was seamless. But I didn't know it was seamless, which prevented me from making progress for a few days.

So, the question is: if an app takes care of a particular problem in a seamless manner (without the user having to think about it), should it tell the user in case they have a concern about that? In this case, it might say, "Fit on the watch works with Fit on the phone to track your steps as long as at least one device is with you. If both are, your steps won't be double-counted." This solves the problem for me, but may confuse other users who weren't worried about double-counting to begin with.

This seems like a no-win situation. Say nothing, and people like me will get stuck. Point it out, and people who didn't think of it will get confused and potentially stuck.

Is there a way out? How would you have designed Google Fit to solve the problem highlighted in bold above?