HUD elements in VR scene look vertically stretched

I have added a crosshair as a texture and a circular-fill material on my hud, based on the default FirstPersonHUD. I notice that although the Screen W & H values and the source textures are definitely square/1:1, on the DK2 they look slightly stretched vertically - they look slightly taller than they should be. Here’s the HUD bp (although there’s probably nothing to figure out from that): . Has anybody else experienced this?