need help helpin a friend

[IALuder]

ok, so since the jeep is still in the shop ive been daily driving the integra for a few weeks now. all is well except every once in a while Ill go to slow down to a stop light and i need to pull it into neutral but the clutch pedal is sitting on the floor with no pressure and I have to pump it to get pressure back into it. Not a huge deal but I just replaced the clutch master cylander late this summer and cleaned all the lines out. Its got 450 degree fluid in it instead of stock. Still stock slave cylander. could the slave cylander be bad or should I not have put so much trust in oreillys clutch master cylanders? Could the fluid be acting up in the cold weather? Im not losing any fluid, its still right where I left it this summer and its still clear and clean. This only happenes about once every 100 miles of driving. Let me know what you guys think