[06 Mariner Hybrid] (hopefully) small problem, please help

Yesterday, my "low oil" warning came on, and I know it's about time for me to change it (will do so tomorrow). Anyway, on my commute home, my 2006 Mariner Hybrid would not go into electric mode. There's a lot of traffic where I live, and I'll always see the RPMs drop to 0 around here, but they stayed at 1000 the whole time, just like a conventional car. I'm hoping it's because the oil is low, and that changing it will fix the problem. Can anybody help me here? Is this problem from the low oil? Or do I need to take it to a dealer to look at it.