Unusual swirls

I use Amazing Clear Cast Plus a lot primarily to wood turn spheres with things in them. I've never had any issues...in fact I won't use anything else. I just had a issue on the piece below where I see swirls in the resin. I am usually fastidious about mixing but this was just a random piece I made one day so maybe I didn't mix it well enough. It was cast and then left to cure for 48 hours under 3.5bar pressure. 

Any thoughts on if that's the issue, it was hot and humid that day if that helps?

TIA