Yes, those times seem a bit far fetched for Webb, but he is capable of running of those times, even this season (though I doubt we will see him run another 10.000).
This was his first track 10.000 and he basically followed Ritz. Had the pace been in the 27:20 area, it is conceivable that Webb would have had the capacity to run in that time zone too.
Remember, last year Webb ran 13:10 for 5000, which equates to around 27:20 for 10.000 at this world class level.
With his combination of speed (1:46/800, 3:32/1500) and strength, Webb has the potential to get close to the American records in the 5000/10.000, but a lot of this comes down to getting into the right races.
Webb is the real deal, and his 27:34 is not that surprising, in view of the training and work he has been doing since last track season.
We wish him every success this season.