First off you are going to get hit with the "no need to secondary" comments but regardless you decided to do so. It is not all that unusual for yeast to get "awakened" after a racking event and result in some further activity. You mention that you hit final gravity...was that by consecutive stable readings or by the recipes' stated final gravity? If by the recipe, that is not always accurate (in fact I rarely if ever hit the stated final gravity). In any case, I wouldn't worry about it your beer will be fine.
@bluemoon373 said it best with reawakening yeast. Will happen especially if it's been only a week or so since brew day.
The greatest concern here is with procedure, accuracy of gravity readings, etc. Yeast will awaken if it hasn't fully attenuated the brew, when you "shake it up" a bit, as with racking. My concern would be tracking down where things went wrong..... And there aren't too many possibilities. The first thing I'd look at what my yeast. Did you use the yeast called for in the recipe. I'd then look at my hydrometer as the culprit. Different yeasts have different levels of attenuation, and those are shown in charts you can find on the internet. Punch your recipe into Brewer's Friend (free to use online), and look at the different FGs listed as you change your yeast. It's a lot actually.
The real concern is with bottling. If you are being "fooled" about FG, you run the risk of grenading bottles. I'm pretty lackadaisical about this because I use EZ-Cap bottles which use the Grolsch type caps (wire bails), and are rated well in excess of 100 PSI. The seals will leak before the bottle explodes. Ordinary beer bottles are not capable of holding a lot of pressure, and are not consistent.
H.W.
Enter your email address to join: