This is fairly common at my organization.
Many times the BA ends up being the subject matter on the particular software or workflow. Once the new process is put into production issues arise with users. Our IT support and application support are the front line to deal these issues, however, the BA can get called in to help with support is the issue is more workflow based. The BA at the end ends up knowing the program in and out moreso than others and are asked to step in when needed.
The role of a BA differs from organisation to organisation. In some organisations, the BA is expectected to know and provide technical support function, in others the BA in only expected to review, analysis and provide recommendation for improvements hence leading to a project which once executed / completed will bring about improving the efficiency of an organistaion's operations.
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