I would just keep an eye out for now you don't want to medicate without a cause, if symptoms progress any further then you will be catching them early and treatment should be successful.
Water changes can help with this disorder because one cause is by a build up of gases, these form bubbles within the body which can cause the eyes to protrude. If you are already doing frequent water changes (in a small tank) then this may not be the reason but you can always try to increase the frequency just to see if it helps.
if he does get popeye and these water changes are not helping it is probably bacteria related and you should use the medications.
if you notice grey with no popping of the eyes I am afraid they may be cataracts which can also be caused by a number of things...but it probably age related.
BUT if you really are afraid it is popeye and want to treat ASAP you could look up the disorder to see what you think. If you feel you want to treat him anyways just in case then you can decide. Just make sure you give the correct dose and whatnot as you probably already know
I would personally try the water changes first though
Hope this helps!