I have personally never had that issue, and I have ran it as high as 3 mg before. It does seem to be a fairly common side effect for some people though. If the flushing passes and you are not having any other symptoms, I probably would not worry too much about it.
I would only be concerned if you start having chest pain, trouble breathing, or signs of a serious allergic reaction. The flushing itself can happen for a lot of reasons like dehydration, an empty stomach, or adrenaline and cortisol still being elevated after training.