ok, all i did was take off my front tire to get it replaced. When I put it back on my front brake acted weird. When I squeeze the brake lever it has no brakes, if I squeeze a second time its got half pressure, a third time and my brakes are normal, hard as can be. I took off the caliper and reset the pistons, made sure the pads were in right and even bleed the brakes and same result. once i pump the brake they are fine, but do the same problem after about two minutes! any ideas?