Sounds a lot like my bank. 5 characters of 0-9 is exactly what they validate their passwords on. Luckily that validation is done only in Javascript, so disabling the check allows you to use any password you want. That doesn't help the average person though.
So you actually tricked the server into setting a password it usually wouldn't accept? Uh oh, hope they don't "fix the problem" by adding similar validation on the server side later :P
