Are the holes on the inside or outside of the tube? Tubes sometimes can be twisted, but usually they sit pretty straight, so if the holes are on the inside they might be from the spokes and if they are on the outside maybe you ran over a carpet tack strip or a stretch of broken glass. Check the tire as well.
If they are paired holes like "snake bites" on both sides of the tube, that is from an underinflated tube being pinched between the rim and a hard edge in the road.
Thanks for the quick response. The holes are all on the outside of the tube. But the "snake bite" description & image is exactly what they look like. Maybe I got a leak from something else, didn't realize it, and the under-inflated tube was pinched a couple times to get those other holes.