Although it's certainly influenced by your grandmothers passing, it's also a poem that stands the test of time - I find it very beautiful 14 months later :-)
I think that's a nice part of art, we will put our emotions in it, and look back at it later with a new perspective, remembering how we looked at the world 'back then'.
Spot on! I often feel this way re-reading poems I've written, it can be like a moment of frozen time. It takes me straight back to where I was at the time emotionally, and in retrospect, new perspective can be gained :)