For the past week or two my front brake will pop the first time I use it. Once used, no more pop. If I let it cool down, say for about an hour, and get back on it will pop and again just the one time. I've checked to make sure everything is tight, the pads look ok and I can't make it do it when I put it up on my lift. I get nervous with anything concerning the front tire or brakes. I'm scheduled to take it in for service next weekend. Should I wait until then or would you go by ASAP?