As an update on my wireless charging with the mophie charger, mine too sounds the reconnect tone every now and then - enough so that I am leery to put it on a pad at night because it would wake me up. I realize I could turn the phone to vibrate which would silence it, but then calls from my Favorites list, which I use for emergencies, would not ring.
That said - I really think it and the Belkin are sensitive to where the phone is placed on the pad. Sometimes the phone can be on the pad for hours with no tone, other times the phone tones/connects twice in a minute. Not sure exactly where the coil is, I think placing it about 1/4" 'high' on the pad is the best place and it won't tone. But I am still playing with it, and wondering if it is a bug or a weakness in house power (for everyone it seems - if you google this issue a little, you will find android phones have tons of issues with this and worse over the years they have had wireless charging.)
So I can live with it - and it's really convenient for keeping the battery charged!
PS -
this article speaks of a Ive's possible future for the iPhone with an eventual 'single sheet of glass'. Part of that vision is not plugging stuff into the phone. I have not plugged anything into my 8 for weeks now, as I get all the charging done by wireless; I have bluetooth ear buds; and I do periodic encrypted backups to iTunes via WiFi. The future is here, don't even need the iPhone lightning connector now maybe.