Hi Michael, that is certainly possible. Something about these specimens looked different from ones that were identified as gunnii but may just be because the latter are on edge of a nice big dam. According to Vicflora the main difference is in the prickliness of leaf margins? I will check those when I have a chance
Sedges are often difficult to ID so I'll put this one in as Cyperus sp for the moment. It may require your taking a specimen to ANBG to get a species ID.