[AdamEL]

I recently picked up a 2013 Cadillac ATS as a daily driver. It's an awesome car. When I bought it, the tires were almost dead, so I went ahead and replaced them with some Goodyears a few days ago. After the mount and balance, the car drove even better and quieter than before, as to be expected. However, today I noticed some very, very mild wheel vibration at about 70mph. That would lean toward a balance issue, but it sure wasn't out of balance when I drove it after I had the work done (yes, I drove it over 70mph then, too). I checked to see if I maybe lost a wheel weight, but everything seems to be in tact, from what I can tell. Does anybody have any ideas what the problem could be? I can't stress enough how mild the wheel vibration is. If it wasn't a Cadillac, I probably wouldn't even notice it...
I'm going to call the tire shop tomorrow and see if they can look at it. These guys aren't hacks, they're very professional and have been doing it for decades. I'm just curious if any tire pros on here could offer some advice before I called tomorrow. Thanks in advance!