it's not catastrophic, I used to drop 4 DKH a day if I didn't dose; coraline algae was the culprit.
it does a lot of harm at the same time so you will have to take measures.
Double check. Keep a track of it and see if it's a regular occurrence, decide how you can address it. Ideal would be a calc reactor but drip dosing or dosing in topoff water will work too.
if you go calc reactor you might still have to dose some alk separately as the alc might be used in greater proportion than calc depending on what uses it.