Yup. You'll get an average of 3.5 after a large number of rolls (for some definition of 'large') .. but it's possible that you won't meet the (3.4,3.6) range based on a string of high or low runs in the random number generator, and your test will fail. At that point the user will go .. "Huh?" I'm not sure what their next step might be -- if they're familiar with module installation, they might try a make test, and see that it passes the next time, and continue on to do the install. And some people might ditch the installation completely.
I'd recommend you change that to a non-critical test.