That's WAI if you don't break compatibility.
I think the only reason behind moving is to have a better sense of progress or freshness. It seems like semantic versioning should support having some date on the minor numbers.
The entire spec is like a 10 minute read. Anyone using semver should have at least read the semver spec. Anyway, the bullet on tagging:
“Build metadata MAY be denoted by appending a plus sign and a series of dot separated identifiers immediately following the patch or pre-release version. Identifiers MUST comprise only ASCII alphanumerics and hyphen [0-9A-Za-z-]. Identifiers MUST NOT be empty. Build metadata SHOULD be ignored when determining version precedence. Thus two versions that differ only in the build metadata, have the same precedence. Examples: 1.0.0-alpha+001, 1.0.0+20130313144700, 1.0.0-beta+exp.sha.5114f85.”