The second question to ask is whether there's any difference between the terms of the warranty and the terms of the maintenance agreement when it comes to these circumstances. If there is, the follow-up question is why.
Bottom line: I'd recommend rewriting the terms of the maintenance to turn it into an extended warranty. Doing so doesn't really fix anything -- you get the exact same specs-versus-bugs arguments that have taken place since the dawn of the software business, but it would eliminate a lot of unnecessary confusion.
Now if you're asking me to fix the specs-versus-bugs problem, by all means, tell me where to send that invoice. If I can solve that issue, I can promise the invoice will be a very big one.
This story, "What a software maintenance contract needs to cover," was originally published at InfoWorld.com. Read more of Bob Lewis's Advice Line blog on InfoWorld.com.