No worries Jan....I did the exact SAME THING with my tris...only I did it to the top and left side. No one will know. I only told you guys and see...you've already forgotten! Thats how unimportant it is!
Now...on to the sashing..hang on...I'm going to measure.
Between the blocks- 1/2" finished,so cut 1" x 5 1/2"
The outer skinny sashing between the center and the tri border is 1/4" finished. Cut 3/4" wide.
Now...don't worry about your row of tris. When you get totally finished, you won't even know which side it is.