I quickly found another similar quote which refers to numerous non creationists who have expressed surprise or dismay about not being able to get older c14 dates from objects which are supposedly carbon dead.
"In testing the Tandem Accelerator Mass Spectrometer (TAMS), a major problem appeared. Normally as in any test with decay counting, background counts must be made. Usually, fossil carbon is used for the background count since it is assumed that the fossil carbon is anywhere between 60 and 600 million years old and therefore cannot possibly have any 14C left. However, as previously noted, fairly high levels of carbon 14 are in fact present in these samples. R.H. Brown reported in Origins 1988(15), p. 39-43 that "infinite age" samples of fossil carbon are being reported in the literature as having C-14 ages in the 40,000-year range. The laboratories doing this research are from Europe, Canada, and the USA (Brown et al. 1983; Jull et al. 1986; Beukens, Gurfinkel, and Lee 1986; Grootes et al. 1986; and Bonani et al. 1986).
"Contamination from our present Biosphere" was the most widely used interpretation to explain the presence of these "unexpected results". The journal Radiocarbon (Vol. 29, No. 3, 1987) contains two different reports from groups that attempted to explore the limits of this "contamination". The first group, from Simon Frazer University in British Columbia (Vogel, Nelson and Southon 1987) measured 43 samples of anthracite (coal) from Pennsylvania, USA, that had been given the best known pretreatment to remove contamination by modern carbon. The sizes of the samples ranged from 0.5 to 20 milligrams. They all yielded around 43,000-year carbon 14 dates, regardless of the sample size. Again this finding was attributed to machine background and contamination during sample preparation. The second group, from the University of Toronto in Ontario (Gurfinkel 1987) stated that "One of the major problems encountered in this study was the apparent presence of 14C contamination in samples that were assumed dead . . . it could not be assumed that even the oldest samples were necessarily 14C free" (p. 342). Gurfinkel, went through a meticulous process using graphite, calcite, limestone and anthracite samples to come up with her conclusions. And, all she could say is that "infinite age" samples should be expected to have "contamination" giving dates as recent as 43,000 years, which is similar to what the Simon Frazer University group obtained. As more and more groups looked at this problem, it has become common knowledge that there is a wall this side of about 50,000 14C years that cannot be passed in practice.
Now, consider that if the "background noise" was really a problem that even if no sample was in the detection machine that the machine would still report background noise corresponding to ages less than 50,000 years. This is not what happens. According to Schmidt et. al., no counts were detected in 30 minutes giving an age greater than 90,000 years.18 Geological graphite was also tested and gave an carbon 14 age of almost 70,000 years. Compare this with "infinite age" samples of fossil coal, oil, bone, ect., that all date less than 50,000 years.17 Certainly background noise cannot explain such a discrepancy."