Dealer had to replace my throttle cable after only 1800 miles. Got to where it had 1/3 inch freeplay with the coupling screwed in same amount as when new and could only get it to a little over 1/4" barely screwing it in about 2.5 to three threads before tightening the locknut.
They took care of it under warranty but had my bike for 8.5 days, so a little aggravating.
Cable stretch is not uncommon - usually the clutch side because it's under more tension, but throttle side will stretch a bit too, especially when you pin it hard all the time (LoL). Could have just been a weak cable -