not a burden

From Saturday morning's game down at Earl's in Gallup, I draw your attention to the upper left quadrant.
"Trove" and "umber" had been played, and I had all the letters for "species" except the C. So I played "am" and actually drew the C (out of ~10 letters left in the bag). Pure dumb luck.
I figured, with AM there to block, and I had 2 of the last 3 "S" tiles, I could play "strove" and move into a comfy lead.
So Mark played "roasted/ram/strove" for 75+ points and killing my chances. Easily the best play of the entire game.
So out of desperation, this being nearly the end of the game, I played across the top making "cumber," a word I/we figured had no chance.
But the 4th edition called it a word, for 107 points, plus I won. Great end-game.