Joist hanger too low?
Okay, thanks for the extra pic. I'll be honest, it looks like a lot of weight for that particular style of joist hanger. If it was my job I'd drill at least one extra hole higher up in the hanger to reinforce that lowest one. 

One caveat, this counts as 'modifying' the hanger, rendering the manufacturers specs/guarantee etc. void (probably). I'd be talking to the building inspector or even the hanger manufacturer to be safe.

The hangers we have in my area have loads of holes...

You could up the specs of the cross nails by changing them to long construction screws...