just recently changed my brake fluid for the front. now fluid leaks out of the reservoir and drips on my arm when im riding.  i filled it higher than the upper mark but i didnt think that fluid should be able to get past the diaphram.  does this mean i have a hole in the diaphram?

DOT 4 Brake Fluid with take your paint off.  I'd take it down to the upper mark in the master cylinder, then see what happens.  Use a clean syringe or something to suck it out.

can anyone tell me for certain that the diaphram should be airtight?

You should not be leaking brake fluid from anywhere in a normal system.

Regarding the diaphragm (aka bellows) its job in life is to allow expansion room for the fluid as the temperature of the fluid increases. No fluid should be getting beyond the diaphragm. While removing fluid until at the specified level, check the diaphragm for a hole, misalignment, or a tear that might be causing this.

The lid of the reservior uses the diaphragm as a gasket. QED - it should not be leaking.

thanks star.  thats the confirmation i was looking for.  i did check the diaphragm when i had it out during the fluid change and didnt see any rips/tears/holes.  i'll take it off and clean the edges to make sure its on right and try again