It's not an issue. They are increasing our value, and if you read the filing closely, they have authorized the purchases within a set price range -- so they will not overpay versus their long-term view of the shares value. Don't forget -- they are retiring these shares. They goosing the P/E, and their ability to increase dividend payouts in the future, as the number of shares outstanding will be smaller, so that free cashflow can go farther. It's a great, shareholder friendly move.
You really shouldn't be involved with equities if your hoping for them to follow that logic. $1 billion will retire 25 million shares at $40 a share. Do you really think they would be able to keep the lid on the price if they bought back only at book value, removing roughly 90 million shares? Do you realize that you cannot restrain the demand side from sending the share price from rocketing if they were somehow able to retire shares at under book value because of the sheer drop in the supply side of the float? They wouldn't be able to remove more than 10 million shares before the share price went crazy, thus completely undermining their attempt to buy them back "cheaper".