Spot elevations--this was cool!

I put spot elevations in my irrigation plans so grade changes are included the hydraulic calcs--that's the extent of my spot elevation useage. I notice that you changed the way these are done recently. I haven't gotten far into the changes, because it still works the way I need it to with just a few clicks of the mouse. But something interesting and cool happened:

I'm working on a project with the grading plan x-ref'd in. I set a spot el by the meter, then started setting several more throughout the site. I had OSNAP on, and I inadvertently snapped to one of the xref'd grading lines, and it's proper elevation was already in the dialog box! IOW, I was ready to type in "75" or whatever the number was, but it was already there, matching the elevation number of the contour line!

How did it do this?

Thanks!