premise: Celtic captain Neil Lennon could be facing a lengthy suspension after being sent off during his side's 1-0 victory at home to Falkirk.
  The Northern Irish midfielder was giving his marching orders for allegedly head-butting the Bairns' on-loan Arsenal striker Anthony Stokes - ironically after winning an injury time penalty.
  Following the red card from referee Iain Brines, Lennon flung his captain's armband onto the pitch before facing up to assistant referee Neil Brand, who had flagged to draw attention to the clash between him and Stokes, and screamed his displeasure at the official.
  He then kicked the ground as he marched up the tunnel.
  In addition to an automatic one game suspension, Lennon could face a further punishment after Celtic manager Gordon Strachan revealed the referee would include Lennon's angry departure in his report.
   What caused Lennon to be sent off?
hypothesis: clash between him and Stokes