Probably a stupid question but Is it okay to go off of a rectal temp for a 1 year old? I know they…

Probably a stupid question but Is it okay to go off of a rectal temp for a 1 year old? I know they stop doing that after a year but I know it's also more accurate. His rectal was 103.3 and his armpit was 100.1 but I didn't think there was that big of a difference between the two methods but I'm also not a doctor. Just wondering if i should stick with it being 103 and call his doctor or go with the 100 and let him sleep it off.