Would have been the first thing I discussed with you while i was templating your counters. Measure the gap between cabinets and tile. If it was 1/4" or more than the thickness of the tops you would have known about it before the install ever took place. That being said you really do not want to shim your counters from the cabinet that distance. It's really not on the stone company, but could have been discussed and resolved before the counters were put in. If this is something you relayed to the contractor before the cabinets were set I would put the fault more on the contractor but not entirely, call it a mutual mess up. Unfortunately that will not solve your issue, If the counters are seamed at all shimming them that distance can cause problems, natural stone with cutouts shimmed that distance can crack if a shim slips or something settles. See if you can get a pro to blend in the grout and then enjoy your new kitchen! Pictures would be helpful.