feels like burning psi in my arm

[dmoney]

the other day, i was playing half life 2 and all of a sudden i felt this burning sensation in my arm. it felt like the psi was building up in my arm, almost like i could do one of those energy blasts from dragon ball z, it was weird. I thought maybe my hand was going to sleep, but how could it? I'm wide awake and playing a first person shooter with an X Box controller. what could that be?