Confusing ESA Letter

I submitted a ESA 50 review form and today received a confusing letter saying

"We have looked at your claim again following a recent change"

Stating the amounts I am receiving at the moment.

Is this a decision on the review? Or have they just decided something changed and so sent this and I might still be called for an assessment?

Adding to the confusion I see they've asked my GP for evidence dated only two days before the date of this letter...

Has anyone else experience this? Yes I could call but would rather not!

Thanks
Ellen