hopefully your new pads just need bedding in.

but if you didnt take the cap off the top of the brake fluid bottle when you pushed the piston in the calliper back (to allow for your new thicker pads).
you may have put too much fluid pressure through your brake system.

have you noticed any brake fluid leaking

my guess is that if you have done this, it would have cracked the brake fluidbottle so check for a leek there.

hopefully just need beding in though
other than that i cant think of anything else that yu can do wrong.
hope this helps