What are the effects of Ag/AgCl electrode liquid interface contamination?

I have been using a $\ce{Ag/AgCl}$ electrode with a porous teflon tip to measure open circuit potential between two electrodes separated by a membrane. I am worried that reagents such as iron chloride and ferri/ferrocyanide have contaminated the teflon tip because we have not been using a salt bridge. 


However, when I place two reference electrodes in the same solution, the difference in potential between them is very low, ~2 mV. 


What effect could having reagents in the teflon tip have on my measurements? 


