Hi, Occasionaly I Cough Up A Flem Like Substance ,mainly

Hi, occasionaly I cough up a flem like substance ,mainly clear or white in color. saw a dr. about7 months ago,they thought it was Acid Reflux . It does seem to be more active or frequent after meals. I have checked the info. on WebMD on Acid Reflex ,but I did not see any thing about coughing up flem like substances. Does this sound like Acid Reflex ? any other suggestions ? Thanks !!