Their inventory floats according to supply and demand and is fairly unpredictable. It is not unusual for them to not have a particular lens in stock.* In case you were wondering, I think it is a little premature to pin this on the Pentax FF announcement. When the camera actually launches, you can expect that prices for used FF K-mount lenses will skyrocket in much the same way they did after the launch of the K10D. For example, I (regrettably) paid $100 for my Pentax-A 50/1.7 in 2007 and felt happy at the time to even find one available to buy.
Steve
* A good example might be fast 50s. Today, KEH had no FA fast 50mm lenses in stock.