Context. Subdwarf B pulsators exhibit pressure (p) and/or gravity (g) modes. Their frequency spectra range from very simple, with few frequencies, to very rich, with more than fifty peaks in some cases. Balloon09 is a hybrid pulsating subdwarf B, showing a great number of p- and g-modes including triplet and quintuplet-like structures, which are interpreted as p-mode frequency splittings caused by stellar rotation. Photometric observations undertaken in two subsequent years revealed a change in these rotational splittings of 0.24 - 0.58 μHz/yr. Aims: We analyse the possibility of angular momentum interchange between stellar rotation and internal gravity waves as a mechanism for the observed rotational splitting variations. Methods: The expected change in the rotational splitting of eigenmodes resulting from this mechanism are computed in the non-adiabatic linear approximation for a stellar structure model that is representative of the target star. Balloon09 is a particularly suitable candidate for our study because the change in the rotational splittings are proportional to the amplitude squared of the g-modes which, in this case, can be estimated from the observations. Results: We find that this mechanism is able to predict changes in the splittings that can be of the same order of magnitude as the observed variations.