Hiring managers and head hunters need to take note of this article.
That said, if your interviewers are doing their jobs properly, they should be able to filter for (or simply ask about) that level of skill awareness during the phone screen.
More likely, when you get told post-interview that "we need someone with more experience in X" it's usually a polite way of saying that they just weren't, you know, all the into you, and are trying to save face on both sides by pointing to something dry and objective, rather than things that actually matter. Like you know, the fact that you were underdressed (or overdressed), all those awkward silences you had with that second or third guy you interviewed with (remember, the one who announced his presence in the room by slouching in a chair and saying "I'm hungover"), or that you seemed to exhibit a slight latency in your recognizing some technical term that's common coin in the circles they run in (and so therefore, you just don't have enough chest hair), etc.
They didn't want a programmer, they wanted someone with known Drupal experience, who could hit the ground running, and wouldn't fall back on writing new software to solve a problem that could be quickly (if not perfectly) solved in Drupal. PHP based content management systems job are only tangentially related to programming. Drupal (and Joomla, etc.) exist so that companies can manage their websites without a programmer.
That may not be fair, but it's how the hiring companies (direct or recruit) will look at. If you want those jobs get a Drupal site or two under your belt, and downplay your 10+ years of PHP on your resume and during the interview conversation.