Repeater sometimes "Locks" after sent power until updated

I was making a mob grinder with some suffocation abilities. I had a block with a redstone torch on the side and 2 redstone dust after the torch. Then I had a repeater put on tick 1 and it turned on like it was supposed to. Then when I destroyed the redstone closest to the torch, the repeater stayed on and it was the opposite of the power going into it
for whatever reason,i cant upload a screenshot, but here is one here:http://puu.sh/1p5nJ