I was riding yesterday down a steep long single track and was riding the back brake ALOT. After a while I noticed it starting to squeak and not much longer after that there was NO BACK BRAKE. The lever just went all the way down with no resistance. I played around with it for a while and thought that maybe I was out of fluid. I checked the level and it had plenty. It was probably more than five minutes by the time I got done checking it. I pushed on the lever again and presto I got brakes back. Kinda scary. Has anybody else had this problem? Was I just riding them too hard too long and the fluid boiled and just needed time to cool? Is there something else I should be checking….the caliper the master cylinder? They seem to be working fine now and I’m gonna drain the fluid, put in fresh and bleed them before the next ride but I just want to see if this is a common problem or if there is something else I should be checking. Any advice would be welcome.