I don't think this is a disaster waiting to happen, it's merely a maintenance chore waiting for you to take care of. That bamboo doesn't seem to spread very fast but you should check regularly for rhizomes approaching that fence and cut them with extreme prejuce. One or two may escape into your neighbor's yard. I would preemptively talk to them and make it clear that you are on top of it but should anything escape your rhizome-pruning efforts you will take care of it in short order.
Nice-looking bamboo by the way.

I usually just sit back and read this forum since I am still fairy new to bamboo. I have had bamboo for a couple of years but none has spread to the point where I needed to worry about anything.

I don't think I would panic, but rather start a yearly root pruning schedule or use a barrier.

Other than the need to do some overdue rhizome pruning, what are you concerned about?

Very pretty bamboo you have there! The place we got our bamboo has a good article on the care of bamboo that you might like. I especially like the idea of making trenches - lots easier than barriers. We got some bamboo that will make a nice screen for the back (south) side of the house.

Here is a link that might be useful: Bamboo Garden - Care of Bamboo