The odd bowler has really troubled him with that line, like Vaas and Flintoff (though Vaas was over the wicket, obviously), but last summer he was in terrible form as well and got out to a number of fairly average bowlers in that fashion. Obviously the plan was successful, as it pretty much always has been to varying degrees against Gilchrist, but he's overcome it plenty of times in the past and did so again this summer.
You can pretty much draw a line with Gilchrist's form when he was rested for two matches during the VB series last year. He came back with 30 odd and a century, and since then he's averaged 40 in ODIs and 36 in tests, which is at least a significant improvement from what he was managing beforehand. He also made a big song and dance in the media about working on the around the wicket line in the buildup to the Ashes this year, and evidently he handled himself a fair bit better this time around, aided by the fact that the ball was doing a lot less in Australian conditions.