They're probably sore or being aggravated by something. If I was you I would pop him along to the vets - could be a multitude of reasons & treatment would depend on the diagnosis
Bathing his eyes with cold tea may be soothing for the time being but should definitely be looked at.
Conditions that can cause sore, red eyes vary from conjunctivitis, ulcers or dry eye & allergy related, to name a few & all require treatment .
Some dogs do seem to have redder eyes than others but I would get it checked out to be on the safe side, if i were you
Let us know how you get on.
Lindsey x