As long as you are being honest with your customer and explain this somewhere.
The problem is one of expectations, if you don't say anywhere what have you prepared for and what are you going to do when something you didn't prepare for happens, you are misleading the customer, as they will rightly assume you have prepared for most ordinary things (heroku outage, for instance.)
The problem is one of expectations, if you don't say anywhere what have you prepared for and what are you going to do when something you didn't prepare for happens, you are misleading the customer, as they will rightly assume you have prepared for most ordinary things (heroku outage, for instance.)