Did you pour the dregs on top of the head? Or was the head just "rocky?"
If you poured the whole bottle, especially at two weeks old, without stopping before the sediment came out, then you just wound up with a layer of yeast on top of your head.
Might make you fart a little, but other than that you're good.
If the head is clean and you left a little beer (and sediment) in the bottom of the bottle, but your head is sort of rocky, that's okay.
"God forbid we should ever be twenty years without such a rebellion.... And what country can preserve its liberties, if its rulers are not warned from time to time, that this people preserve the spirit of resistance? Let them take arms.... The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants." - Thomas Jefferson, in letter to William S. Smith, 1787