That's exactly what happened with mine on my second diff. It popped on turns for a few months then progressively got worse until it popped going straight too.

It could be an axle tho. I hope for your sake it is.

I live in Detroit, I couldn't give a **** how good my car is in the "twisties." "I could use a hundred people who don't know there is such a word as impossible." ~Henry Ford