'As' here is used in the same way as 'while', so the inclusion of a comma doesn't make sense. I would remove it. :) It doesn't assist the flow either.
Other than that, incredibly seamless writing! It veers on the dreamlike. I would avoid the overuse of adverbs such as 'slowly' and 'carefully', and instead try to focus on the strength of your main verb. I think 'stroke' is an odd choice. If you take 'caressed' for example, the stanza reads better, and the added sibilance contributes immensely.
The title of the poem is perfect by the way. Its surrealism and mystery was really enjoyable. :)
i really loved your style here. it's very refreshing and different. The word choice were very atomic indeed and the overall scene is kind of visual. It's a very appealing poem! I would have loved to nominate it!
There should be a comma after lingering, but apart from that. I really like this. It reminded me of 'a picture of dorian grey' for some reason. Lately your poems have a surreal feeling to it, I'm really enjoying that.