It SHOULDN'T cause any problems, under normal circumstances but something does come to mind.
I'm assuming here that you had your fone plugged into the charger cube that Apple supplied with it originally and that was plugged into a common wall socket. While I can't speak for the overall "robustness" - spike-wise - of the Apple charging cube, there IS a possibility that it may pass transient electrical spikes through the charging cable to the fone.
If you use the charging cube directly plugged into a wall socket, there are two relatively simple things you can do to help reduce this possibility. 1) get a voltage spike reducing plug-in wall block at a local Lowe's or Home Depot, plug that into your wall socket and then plug your Apple cube into THAT or 2) again, from Lowe's or Home Depot, purchase a new wall socket replacement socket that has a built in USB charging port and replace your current wall socket with that, then plug your Lighting/USB cable directly into that.
Either of these two modes should reduce the possibility of surges being passed to your phone. Both are cheap enough to add a level of protection to the charging circuitry.
Of course this also presupposes that you're NOT leaving the phone plugged in continuously even after it's reached it's charging potential. Leaving them plugged in for more than 12 hours isn't good for the battery itself.