Bubbling after 3 weeks

20 batch rookie here.
Is it unusually for a fermenter to start bubbling again after 2 weeks of no visible action? This 2.5 gallon batch bubbled for a day or two and stopped for about 2 weeks. Then several days ago it started back and is still bubbling about every 20-30 seconds.
Thanks for the thoughts!
Mitch in Southeast NC

[quote=“MitchInNC”]20 batch rookie here.
Is it unusually for a fermenter to start bubbling again after 2 weeks of no visible action? This 2.5 gallon batch bubbled for a day or two and stopped for about 2 weeks. Then several days ago it started back and is still bubbling about every 20-30 seconds.
Thanks for the thoughts!
Mitch in Southeast NC[/quote]

Its probably just CO2 and/or other gases coming out of solution. The only way to know if fermentation is happening is by testing gravity.