The fabric manufacturers have been inching up their prices over the last several years, 10 - 25 cents / yard increases, usually one price increase per year. It adds up.
Several factors have played into this. For a time, the US dollar was weak, and since nearly all of the fabric is produced overseas, this caused the price to go up.
When the cost of oil was up, then that meant that transportation costs were higher, and the fabric travels from the far east to west coast ports and then by truck to distributors, then by truck again to your LQS.
The latest word is that the mills overseas that produce the greige goods (unprinted cloth) have been significantly raised their prices... and I think that is what is driving the most recent round of price increases.