Let's say some customers use version two of your product, and some have upgraded to version three, and that upgrade is not a decision made lightly.

Say the last version of version two is 2.3.2, and version three is at 3.0.3. Now you find a vulnerability that absolutely needs to be fixed, so you release 2.3.3 and 3.0.4 on the same day. Can you see how the release date is totally irrelevant? You may have stopped work on version two in 2013 and only released some essential bug fixes since then. The date is irrelevant compared to the version number.