I want to say something very stupid, but what do you where on your feet when you are walking around your home?
It might be you are being charged with static electricity and the phone is acting crazy with it.
touch your screen on a metal surface in the house, and get rid of the static charge, then wear something else when you are walking in your home.
Now really, how crazy do i sound?
I would seriously test it, what could go wrong
Of course not all owners will have heard of WC
Yea that could be the issue. I am reminded by the same situation with the Nexus 7 2013 gens having the same "grounding" issue.
The only time that i ever had the phantom touch issue (lumia 930) is when i used a different charger, it was a gray market charger. As soon as i plug my 930 in, the screen starts to flicker, click, and drag... as soon as i remove it all went back to normal.
Could this mean the battery of his 1520 is releasing the charge more quickly... maybe :S
Hard Luck OP.
PS. I get the phantom touch issue on both my surface and my laptop...
Also i have very sweaty hands.
I am sharing things with the hope we find a common factor.
Can I suggest that those with the phantom swipe try something ? After 18 months my 1520 started with it the odd time or two, not enough to cause a problem but then it became much more frequent. On one occasion when it was having a really bad spell I noticed that it happened as I touched the memory card access door. I took the card out, cleaned the contacts and replaced it and the problem didnt happen again.
Three weeks ago I replaced the battery in the phone and in the process clumsily damaged the screen so I installed a new screen assembly as well. All was fine for an hour or so and then the phantom struck again, much more frequent than before as well. At one point it was really driving me crazy and I remembered what I had done before, so I took out the card and cleaned it and installed it again, ensuring that the drawer slide in firmly, and I have not seen the problem since.
Coincidence maybe, but it may be worth you trying !