All those who wanted me to count all the candles and make positive that there were twenty-eight may rest easy. I did, and there are.
Comedy/Tragedy: The only celebration in Garfield that warrants this kind of week-long buildup are major holidays... and sometimes not even those. But every year we have lots of time to get ready for the gala celebration of Garfield's "birthday", which is the symbolic representation of the strip's debut on June 19, 1978. On major anniversaries, sometimes the prelude-to-a-cake strips will go on for weeks before the blowout... all a gala celebration for an event that Garfield hates because it reminds him of aging and thus death. The most celebratory time in the strip is potentially when the title character is at his most miserable. Which only serves to remind us why Garfield's birthday is worth celebrating!
Comedy/Weird: Okay... so... Garfield-the-character's birthday is supposed to coincide with Garfield-the-strip's birthday. That would be fine, but the logic is extended to mean that Garfield's age is the same as the comic strip. Which means in the very first strip, Garfield had been born earlier that day. He should have been a tiny kitten, slick with afterbirth. Ponder it!
Personal aside: One thing that's cool to me about Garfield (among many, many things), is that because the strip was created in the same year as my birth, I can always remember how old Garfield is turning. More often though I use Garfield to remember how old I will be later in the year.