6 & 8yr old have sour throat no fever no other symptoms acting fine when should we see a doctor, can it be strep?8 yr old had untreated strep 12wks ago

Strep or virus: It could be a virus or it could be strep. You can watch this and if improved in 24 hrs then it might be viral. If not improving, i would have them checked for strep throat, as the only way to really know is to have them tested.

Sore throat: Sore throat is a symptom caused usually by an infection but could also be from mouth-breathers after sleep, any trauma, acid reflux to name a few. The fact that your 8 yo has a history of untreated strep makes me nervous about heart and kidney complications.. Please have them checked for strep by your pediatrician.

Maybe : Sore throats have many etiologies: strep, environmental irritation, allergies, viruses, post nasal discharge are just a few of them. Strep is usually associated with a fever, so it unlikely, but not impossible. If sore throat persists, or other symptoms develop (especially headache, fever, vomiting) see the doctor.