Hi there --
Given the mildness of the injury and the time that's pased, moderate alcohol consumption really should not be a concern now. If you've had no additonal symptoms since, then you should be fine. It sounds like it was a very minor concussion and should be totally cleared up by now.
Again, as always, moderate alcohol consumption is okay. It should cause you no problem at all.
Good luck to you.
John Kenyon, EMT, CCT
Non-invasive cardiology tech, Emergency and Critical Care technician, Critical Incident Stress Mgmt. specialist