The warp I left between the two mats was not long enough.
I struggled to tie an overhand knot and the wee bit of fringe left is fuzzy from all the fussing I'm doing to it.
I tried using a tapestry needle and then a crochet hook to help push the threads through the loop to form the knot.
Then, light bulb moment, instead of pushing threads what if I pulled them through the loop.
I got my E-spinner tool kit out and used the forceps. It works nicely.
Yes, it's tedious but I won't be making this mistake again.