This sensation would seem to be more connected to the sun meditation than kundalini activity. I say this primarily because it is similar to the sensations that arise when meditating on fire energy, solar energy, etc., such as in the condensation of elemental energy. The solar plexus is the point at which we exercise control over our breathe, and is therefore also the place at which we assimilate energy to be stored in the dan-tian just below and internal to the navel.
Kundalini is specifically the latent nervous energy in the spinal cord, specifically at the root of the spine. It is the potential energy of the nervous system released after the nervous system (the physical, organic system of the body) has been toned and prepared such that it is able to handle the refined energy.
If you have been practicing yoga every day for some time now - a year or more - and your meditations center primarily on emptiness and being, with very little visualization, then it is a possibility.
There's a lot of information about kundalini on this forum, and a lot on the internet, however I personally am disinclined to believe the majority of it, especially that regarding the 'raising' of kundalini. I was fortunate to speak with the spiritual master of a friend - that is, a woman she accepts as a spiritual master - who is in the vedic/yoga tradition. She did not talk about kundalini specifically, but she had to say about meditation in general this: "that imagination is strong, then this is good, and to dream is healthy; but meditation is about emptiness. If we use intellect to meditate, mind is still clouded. If we use imagination to meditate, mind is still clouded. When mind is empty, then consciousness will awake from dream."
I spent time considering her words, and came to the conclusion that there must be a difference between 'chi' and 'kundalini'.
Eh, in any case before using a term like kundalini, I would spend some time studying it from its cultural context, not to berate you for considering it, but the majority of the time I have heard it referenced it has been taken into consideration without the support of the literature and theory that do very well to document this phenomenon, it symptoms, etc.
If you're interested in kundalini phenomenon, you might consider a book by krishna gopi,
"Kundalini: The evolutionary energy in man." For it's discussion of kundalini phenomenon from a personal point of view of Gopi himself, as well as his later musings on the nature of kundalini, I found this book to be most helpful understanding what kundalini is and how/why it arises under the conditions that it typically does.
peace