They've been running into this situation at my MAC store too - certain items, like the P&P highlighting pens and the Supreme Sheen lipsticks, come in, fly off the shelves and then don't get a restock for months, no matter how strong their volume is. Weird supply issues at the corporate level.
Yeah it's weird when perm items are sold out and don't get restocked for a while. The same thing happened with the Prolongwear concealer in my area, too! I went to three different MAC counters and they were all sold out of NW20 Pro Longwear Concealer, I was skeptical and hoping that they didn't discontinue the shade because it's my HG under-eye concealer! The website was sold out for a bit, too, but once I saw it available I snagged a bottle even though I've still got some left in the one I'm using now.