Interesting question. My first thought without doing any research would be no. I could see it being problematic more so for those allergic to pollen from the particular plant (do banana plants have pollen that people are allergic to?) or even those allergic to mold that grows on the leaves. I do, however, assume that anyone highly sensitive to bananas would want to avoid banana leaves and might avoid many fruits and vegetables from markets where they could have come into contact with bananas, anyway, if washing wasn't enough to prevent cross-contact reactions.
Trying to think about my own allergies... I am extremely allergic to grass - as in systemic reaction requiring epi to grass SPT. If I dropped a piece of fruit on the grass would I eat it after washing? Most likely. If I got something wrapped in peanut plant leaves, though, I don't think I'd touch it with a ten-foot pole. I can't explain my reasoning.