This is exactly right. I actually worked as an oddsmaker before. One of the biggest misconceptions out there is that "Vegas" puts spreads at who they think will win and by how many. That's not how it works at all. The spread is based on how you can ensure even money coming in from both teams. That is the main goal. If the line is -2.5, that means there is more early money coming in on Texas A&M. Probably from the excitement of Elko, the deep pockets of betters, etc.
For example, when the spread moved from -1 to -2.5 when ND's left tackle got hurt, it wasn't because we would think the Aggies would then win by that much, just the perception of what the public would think.
Honestly, if you want an indicator of who people think will actually win, check the spreads leading up to kickoff. Smart money doesn't usually come in until gameday. My guess is that this spread would shrink .5 to 1 point before kickoff because I would bet that the ND betters would wait closer to gameday. Just see how I see it playing out.