Affect of barrel aging or infection?

Ingredients
1

I made a barleywine in March, 2018 and put half of the fermented beer in a barrel and the other half in a keg.  My intent was to have enough beer in keg to blend if I needed to. After about 1 month in barrel, the airlock started bubbling and has continued to bubble for the past month. I pulled samples from the barrel and the keg and compared the pH and refractometer gravity today and there are differences.

This is my first experience with barrel aging, so I’m not sure exactly what to expect. I was careful with sanitation, as always, so I feel the chance of infection is fairly low. Both samples taste good and don’t show any off flavors or other indicators of infection. Cause for concern? I’m planning to test again in 1 month to see if there are additional changes.

Left side is the kegged sample pH (3.98) and the right is the barrel sample (3.82)

Left side is the kegged sample (1.044) and the right side is the barrel sample (1.041) Yes, I know this is not actually the specific gravity, but it’s a simple way to compare without wasting a lot of beer.

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Do they taste different other than the expected barrel flavor in the barreled beer? That would be a strong indicator that what you have is an infection.

What you see could be attributable to perfectly normal barrel aging behaviors. The bubbling airlock could easily be residual fermentation by your brewing yeast or CO2 offgassing as the beer warms with the seasonal change. The change in gravity and pH could easily be the result of the beer taking on whatever spirit was in the barrel before. But those are also indicators of an infection.

Other than any unusual flavors, are you seeing any film on the beer surface or weird floating blobs in the beer? Does it smell bad in the barrel when you remove the bung? These would suggest an infection.