Just a warning for those working towards items from the current event.
I visited the vendor Jeelvic to buy a pet and crystal. I had 143 of the DNA on me, which had to be in 2 stacks. One of 44 and one of 99. The pet costs 60.
After purchasing I only had 39 remaining. The vendor took the stack off 44, then instead of takign the balance from the stack of 99 it took the full 60 from the 99 stack as well, leaving me with 39...effectively I paid 104 for the pet which should cost 60.