As far as I know never have seen in relationship to liver flushing. Read it on other forums. It is often from not being able to digest proteins well, but it can be a lot of other things too. Safest thing to do is get a doctor's urine test at least you will know what you are dealing with.
May be it is from certain supplements. Did you do a search on All forums, because it has been discussed in different forums. In the beginning of iodine, may be 5+ years ago, it came up too but I can't remember if it was related to it. At least drink enough water.