Has anyone noticed gas is BAD lately?

[Sato]

I just finished putting in a new head gasket. I think I got a bad load of gas.{pump premium] After filling it up it started to detonate and I think it hurt the gasket. After the repair I ran a load of Techcron injector cleaner and finnished off the tank [gently] . I then filled it with 93 octane Mobil and still found some detonation although not as bad and had to back off timing 5 degrees even after uping fuel pressure. I run the 1S system with a 1mm jet that turns on at 8 psi boost. I use water/methanol 50/50 mix.
I did move the injection nozzle closer to the intercooler by about 5 inches.
I have checked the WI and it seems to work fine. I just wanted to know if any of you guys in the states have noticed that gas is real bad these days or is it just a problem with my setup.
Thanks,
Sato