The answer is: almost certainly. I've run into two situations like this (in other people's yards). One retaining wall was 2' high and one was almost 10' high. In each case the rhizomes went under the retaining wall and sought the surface on the higher ground. If you want to avoid this, you will need to put in a containment barrier between the bamboo and the wall. Good thing you asked now, because bamboo removal with this type of physical arrangement is really hard.

Thank you much. I've canceled my order of bamboo. My yard is full of Eucalyptus's roots. It won't be easy to dig up to put containment barrier.

Thanks,
Gogrrengo