There is a small risk, but it is quite low as long as you take sane doses of 4-FA, start low and titrate up slowly to avoid any issues. You could also skip your dose of 5-HTP.
5htp tends to give serotonin syndrome when mixed with other serotonin releasing drugs. You don't want to risk it, some people get it easier and some it's harder to get. But trust me, i'm pretty sure iv gone through serotonin syndrome and it's worse than being piped on bad ecstasy pills.