(Technically I suppose it's US-1 Alternate, as the official US-1 goes through downtown Fredericksburg, but I think most people just regard the alternate as the main US-1 route.)
Hasn't been that way in 40 years. CTB moved mainline US 1 onto its existing route (the old ALT route) and made the Business Route downtown in 1971.
I wonder if putting it between 130 and 133 would make more sense, assuming it could be fit into that stretch what with the southbound rest area and the crossing of the Rappahannock.
It's a tight fit and would require additional right-of-way between the Cowan Blvd and Fall Hill Ave overpasses, but it's doable. However, rest area traffic would have to use the "cash lanes".
If the goal is to minimize the potential for shunpiking, then here's a better idea: considering that the plans for the HO/T lanes will take up the median down to Massaponax (south of Exit 126), keep the mainline toll plaza between 126 and 130 where there's a wider ROW available, build C/D roads at the interchanges at VA 3 and US 17 (one already exists northbound at 17), and toll the ramps to/from the north at VA 3, US 17, and Centerport Pkwy. This would "ensure" that any shunpikes would have a lengthy (about 15 miles) trip through the stoplights on US 1.