Which edge, inner or outer? If outer, I'd suspect they were just left on the front wheels too long, put them on the rear and get what left you can out of the tread before replacement.
Pulling is just toe, if it still handles okay (and not aged out with poor traction), then I'd run them and get an alignment check with your next set of tires.
You stated you bought it with 37K mi and rotate at 6K, but not the specifics, like whether there was uneven wear when you started doing that, or how many miles you've put on since then.
Long story short, they are not too worn to keep driving on them, but you have (probably) a little over 1/2 tread left so up to you to decide whether an alignment is worth the money. I'd base it on the age of the tires, but also their value, the make and model, and the replacement cost to get what *you* want.
What model year vehicle and how many miles? After a certain point, suspension bushings wear and alignment changes, then you decide, do you want to align based on wear, or replace the worn components. Do not align and THEN replace worn components.
Too many variables, my head just exploded.