Not here, I have close to 10,000 mi on mine, I've never even had to even tighten the cable on the RD in that time, but it sounds like something that SRAM's two-shifting-directions using one single-direction-lever design might be susceptible to over time with wear. Not at 1000 mi.

They're a great company. Take your bike to the shop, show them the problem. The shop may have to take the shifter off and send it to SRAM to inspect and repair or replace, but maybe the shop can get a replacement shifter shipped to them while you continue to ride i, then call you, and you can schedule a quick while-U-wait change, and not miss a ride, and then SRAM can examine the broken unit after the change-out. That would be best for your interest.

If the shop is SRAM-authorized to disassemble and replace a defective internal part on site under warranty, that should work too.

Unless evidence is found of abuse, you should get a new shifter or internal part replaced at no cost to you.