As others pointed out he's assumed the Void/Oneness/Ko'di ... as several others have throughout the series. I'll give you that the vivid descriptions in this passage certainly takes it a step further than other scenes we've seen so maybe Galad had tapped the Source without knowing it... Given that Galad is in his late 20s he's a bit of a late bloomer to have the spark though. Although I don't think he's beyond the range completely. Narishma is of an age IIRC and he was a sparker that had not hit it yet either.

Personally my biggest reason for questioning it is a simple question of why? There seems to be no reason for Galad to become a Channeler this late in the series. But maybe RJ had a specific reason.

Gawyn is more likely, IMO, to end up Channeling since he's so attached to the AS and Egwene. That and it's always hard for me to think of Channelers being romantically attached to non-channelers, it's a recipe for pain since Egwene will live for 300 years (or more if they abolish the Oaths) and Gawyn will be dead in what 60 or so? Not to mention how he'll be an old man and she'll be a young vibrant woman still.