Got my guitar around june and sent it for a setup.

After around six months of playing, I feel the string action on my guitar, particularly the 3 higher strings, has raised. There is also slight buzzing on the low E, but nothing that would choke bends or frets, problems which I don't think I had six months ago.

Is it true that the neck changes when you change strings and don't block the trem? I was cleaning my fretboard about a month ago and I didnt put strings on it for around 1 hour, and I never block it if I choose to take all the strings off.

Hopefully my neck isn't permanently twisted or warped because of this.
No. Your neck won't be damaged in any way by anything like that.

Guitars: Ibanez SV5470F, Ibanez Xpt700, Fender MIM Standard Stratocaster ('04-'05), Jackson Ps-2
Ashton AG200,
Amps: ENGL E530, Bugera 6262-212,
FX: TC Electronics G-major 2, Behringer EQ700, Morley Volume / Wah
Changes in weather and humidity can cause the wood
and string tension to change!! You can do a simple
truss rod adjustment to fix the problem.
Ibanez AEL10E BLK- W/ Graph Tech Nut, Saddle and Pins
Duncan Woody XL Pickup w/ stock fishman EQ

Schecter C1+ Darksunburst w/ SH-4 (N) & SH-6 (B) 24.75"
Gain boost Switch
11-14-21w-38w-49w-60w D'Addario strings
ENGL Fireball+Savage+Vader Cab