Generally bright red blood on stools isn't too bad a sign, probablary means anal fissure - bleeding from the rectum.
but certainly go to the docotrs to get it checked out - they will check it there (a finger up the bum, no harm done.) and then and ask for a stool and blood sample.
might also need a sigmoidoscopy (camera about the size of your little finger placed up back passage to check if anything is amiss).
DEFINATELY go to docs asap and get it checked out, though i imagine it will be something minor it is always worth getting checked out.
Quick question though (you probablary wont know the abswers)
-Does he pass stools regularly. has there been any change recently in consistency, colour, or frequency of number 2s.
-any recent illness, weight loss, shortness of breath, dizzyness, pain...