Rough idle after low octane gas

I recently (accidently) pumped my tank full of 89 octane. Sonn thereafter, the engine started running fairly roughly. With about 1/4 tank left, I refilled with my standard 93 octane. I've driven 80 miles (5 gallons worth) and the engine is still running fairly rough. I would have thought that the engine should have smoothed right out if it was the low octane gas, which now has me worried that either the low octane gas has tainted/damaged something, or the roughness is just a symptom of something else.

Should I wait for a few tank fulls to see if the problem goes away, or get it to a mechanic?

Thanks