From what I understand...at the 5 month point, your grafts have more or less evolved from "grafts" to "hair growing on your head" (actually, I'm pretty sure they eveolved long before now). So aside from scalp trauma that would harm non-transplanted hair, from what I understand, your only concern is the bump and any associated headache...
Hey, I did bang my head in the shower (wasn't drinking yet). Things seem to be growing (slowly). I will start drinking in the shower so I will have an excuse next time.