Replacing the tank didn't cause the ink consumption. Starting your new print job did right after you put the new maintenance cartridge in. You can pull a maintenance tank in and out of the printer at any time and no ink gets consumed. It's the start of the print cycle where the printer decides to preemptively run a cleaning cycle which causes the ink consumption. If your printer hadn't printed in a while it initiates increasingly aggressive cleaning cycles corresponding to how long the printer has sat from last use. Also, fully unplugging the printer or brief power failures at the outlet supplying the Pro-1000 will reset the internal timer and cause the Pro-1000 to "think" a big power cleaning cycle is required.
That said, I usually see about a 58ml jump in the weight of the maintenance tank if the Pro-1000 has not been used for about two months even if it was left in sleep mode and now power failure occurred. If it has printed a few days before, a much smaller cleaning cycle (a few ml) will be performed. At around 2-3 weeks of non use, several ml of ink will get consumed. The mother of all cleaning cycles (58ml every time I checked by weighing the maintenance tank before and after this major cleaning cycle) occurs at around 45-60 days of non use. That seems to be the extreme situation. Hence, you may be the new record holder for ink consumed when getting your printer back up and running, or the Accounting manager got it wrong. 
I have had some of the ~58ml jumps previously as well, and have also previously seen big jumps together with the forced replacement of full maintenance tank (two times). It made a several minutes long whining after the new maintenance cartridge came in. Sounded very intense. If it sounded as the previously observer ~58ml I don't recall. I was making me a coffee after installing the cartridge, and worried somewhat as I could here the faint screaming of preparing printer.
The printer has been idling for 2-3 weeks, but done so several times before with much less cleaning. And as I've seen before, the biggest jumps have been related to full maintenance cartridge replacement (triggered by print job) - those have been bigger than normal. Have yet to experience a forced cartridge replacement jumping less than ~50ml.
Total print time was almost 40 minutes for those four pages (highest quality), so it did play around quite a white within those minutes while preparing.
Indeed the ~100ml is at least a personal record. Not a proud one. Prints came out fine though, but at that total cost, they better do

.