It's real easy to crack very dry leather , esp when it's stretched over a flexible substrate .... (it happens with old sports mitts , boxing gloves , furniture & all sorts of stuff) a quick blow , or a quick flop on a chair can do the job in no time flat .
Dry rot can be a problem too , in some climates , living/hiding on the split side & out of sight . 
If your item is really that dry , oil , oil & oil some more ! 
Aside from it having a blem , I hope you love sitting in your chair , capn !
Thank you!
I do really like the chair, I think that's why I'm trying so hard to figure out if I'm the one who damaged it!
But it's really only cosmetic...I guess I just need some time to get over it
