Jules, I haven't had a mammogram yet, but I'd imagine the word 'concern' in this context covers such a wide variety of things, including even the image just being a bit dodgy / unclear, to perhaps shading caused by the angle not being quite right.
You have been through an awful lot recently, sounds like your nervous system is in overdrive which is understandable. Totally get this is really worrying, I'd be the same, but I think you may be reading something negative into the word concern that probably wasn't intended.
Try also not to make the link between the vagifem and the recall, it really is such a low dose compared to systemic hrt, and even that is low risk.