My best guess (and it is a guess) is that the sellers let the retail buyers run the stock up to $22 to generate some more buying interest. Today is a little different in that I have seen larger purchases on the tape.
What is a little strange in that I have seen a constant bid of about 180 lots at $21.99. The ask has been $22.00 but the lots offered have generally been under 10. So it seems that there is a lot of shares being held to eat up the bids.
My hunch is that the buyers are going to run out of money before the sellers run out of shares, but who really knows. I was going to wait until the shares drop below $20 to buy, but if the sellers run out first the stock could run fast. So I will probably buy some today and then wait.