Kelly - I am SO happy to find this. I have been losing sleep over iphone and my geoform and this secure image bug was source of my problem. Not sure why this particular post hasn't shown up in my previous searches so I'll try to add some additional tags.
I had found the http and https problem for accessing the form - in order to get locate me button to work - but that fix didn't transfer to Apple platform. For iPhones, the locate me button showed up but the "Location could not be found" error popped up whenever you tried to use it.
Looking forward to a permanent fix with this https problem - for me, merely changing the path to my image allowed #location services to work for all platforms.
Thank You!