What synthesizer are you using? I've noticed this with the Dectalk USB. It foolishly assumes that a number followed by the month is a date. I've always found it annoying when synthesizers try to interpret text as abbreviations or acronyms when it isn't. A great example of this is the Microsoft text-to-speech engine which tends to pronounce "sun" as "Sunday" if it has a period after it. This would result in reading "www.sun.com" as "www.Sunday.com." Fortunately, the Dectalk USB isn't that stupid, but it does sometimes botch things up as in the example you gave of the Pine message index.
