This week I released a patch from David Olsen which is a significant change to how pde/build calculates feature version suffixes. The details are in bug 157049, as well, the problems outlined in bug 162020 are fixed as a consequence.
The biggest thing to note is that the major, minor and service segments are now included in the calcuation. This covers the case when a plugin decrements its qualifier and increments, for example, the service number.
These changes will be in 3.3 M5. There may be cases where these changes could cause a one-time decrease in the version suffix, so builders picking up these changes are advised to increment their feature qualifiers.