Most shop techs think core center when you say "center them". Core center is usually back from true center unless its a symmetrically designed ski. If you said "center", its not necessarily their fault. Thats why you always tape out and mark where you want them mounted, make it obvious, post-it notes, masking tape, sharpie line with arrows, anything. This goes to anyone, if you want them mounted somewhere else than recommended, mark it out yourself and make it obvious. If you said true center though and they mounted core center, you may be able to get a free remount. Be polite about it though, don't act like a kid or the shop guys will just hate you more.