How to determine if my rear axle is bent? When riding, the rear wheel feels as if there is a tiny pebble, stuck within the thread.

The wheel is one week old, the hub is Shimano FH-M475. I have done only very tiny jumps - for example from curbs, but could have landed badly a few times i.e. directly on the saddle. I am 70kg (154lbs).

I don't have rim brakes, so I can't determine if the rim is bent. However,visually, it is fine. My rear tire runs at 4.5 bar (65psi).

Is the axle bent? Is it my fault or can I claim warranty?
To my mind, a 'feeling like a small pebble' suggests something in the hub itself, perhaps a failing bearing. To test for bearing damage, hold the axle in two hands and spin on he wheel. See if you get a regular catching feeling that would suggest a damaged bearing or bearing surface.