Software Warranty after completion ?

If after completion of software development the user remembers some new feature to be added; then it means that software requirement specifications SRS document was not written properly and lagged completeness, am i correct? Contrarily, if some software bugs were found after delivery of software to the user; then the developer is suppose to remove the bugs, as per the terms of the contract; and as software is still under warranty; kindly enlighten!!!

 In requirement analysis phase, requirements are finalized and SRS document is signed by both parties. Signing means both sides are agreed on all the requirements mentioned in the document. This is scope of project. After this step, we move to the design phase. Since signed document is a legar proof of agreed requirements, so the scenario you have described can never happen. Software once delivered then addition of new features is part of maintenance now. User will have to pay cost for this separately.
Software testing phase is aimed at removing all errors/bugs/ problems in a software system. Testing team checks software with every possibility and delivers it when it is correct. Bug-free software delivery is responsibility of development team.Exceptionally, if some software bug is found after delivery of software to the user; then the developer is responsible to remove that bug.