The most vulnerable part is the riser, not the bolts. You might want to remove the bolts and make sure you don't have any pulled threads from the risers; if OK I'd install some new bolts (discard the old ones) and call it a day. Btw, you're definitely not the only person around here who overtightened stuff. I've got a feeling pretty much any of us who've turned a wrench have made similar mistakes, so don't worry about it.
Btw, another tip you may not be aware of. When you're dealing with a bar clamp designed like this one, you don't need to worry about getting your torque wrench on those front inaccessible bolts. Just get them snug, then use your torque wrench on the opposite bolt. As long as you don't bottom the top half of the clamp out on the riser portion (leave a gap on both sides), the load on the two bolts will be equalized. If you need to be convinced, try it on one of the other clamps where both screws/bolts are accessible, like the one for the brake handle and master cylinder to handlebar. Finger tight on one, then use the torque wrench on the other, then check the first one with the torque wrench. You'll find the torque is equalized for both fasteners.
Jerry