Iphone 5s fixed itself?

Hi, I have an iPhone 5s which I've had for about 2 years now. About a year ago I got water on it while(foolishly) using it in the bathtub. Immediately after I could tell that water had gotten under the screen, as there were marks. Over the next few days my phone would glitch every so often. Glitching included ghost touches(phone reacting to touches I didn't make) and non responsiveness. It progressively got worse over time. Eventually I figured out that if I restarted it and left it off for a while i would get about 10-20 minuets of good use, before it would start to glitch again. I did however give up trying to use it about 3-4 months ago and let it die and didn't charge it or mess with it during that time. Just today I plugged it into my MacBook to see if I could salvage some photos and it charged up. I unlocked it and its been working just fine. No glitches whatsoever. Its only been about 12 hours since I first booted it up but It seems to work just fine. What causes this? and can I expect it to keep on working or will it just start glitching again tomorrow. Im quite puzzled on this as I was sure I had water damaged the display or something. Any help is appreciated, thanks!