FCC callsign with incorrect group letter

I just passed my technician exam and received my callsign from the FCC (KC1KHV).

I was surprised by the two letter prefix, which seems to come from the class D group. According to the FCC documentation on the topic, a technician license should come from the class C group, which has:

• A K, N, or W prefix
• A region number
• A three letter suffix

I see that it says

When the call signs in any regional-group list are exhausted, the selection is made from the next lower group

but there are clearly still class C callsigns available (I have my eye on a vanity callsign which falls into this category).

What's up here? Am I just misreading things?

• You wrote KCIKHV but that has no number. Did you mean KC1KHV? – Kevin Reid AG6YO Sep 22 '18 at 14:36
• Congratulations on the new license! – Glenn W9IQ Sep 22 '18 at 15:02
• @KevinReidAG6YO I did mean KC1KHV and I have no idea where that "I" came from :) – larsks Sep 23 '18 at 1:18

When the FCC issues your first call sign to you, they do not look backwards through their list of assigned call to see if there are any unused calls that they can reassign. Instead, they use a sequential numbering system from a block of previously unissued call signs. This is the so called sequential call sign assignment since it is simply the next sequential call in their list. Technician class licensees will currently be issued a sequential call from the class D pool.

Based on your sequentially issued call sign, we can see that in district 1 the FCC is currently issuing licenses from the KC1K sequence. After issuing the 626 possible calls in this group. They will probably move onto KC1L. For every prefix group, there are approximately 16,900 issuable call signs. After exhausting all of those calls, they will probably move onto the KD1A block, etc.

But now that you have your new license, you are free to apply for any available group C or D vanity call, which includes a 1×3. Good luck!