No Start

'08, 38k miles, FMF pipe & programmer.
Has been bullet proof for 7 years. Wouldn't start last week. Cleaned the spark plug (my only spare was a used one and didn't spark as blue as the one in it), put in a clean air filter (it needed it), and it fired up instantly.
Rode it a few days to restore my confidence in it, then loaded it down and rode to SLAP (a record small turnout). Had three great days of riding. Wouldn't start Sunday morning. Just cranked and cranked and cranked.
Neuner suggested trying to pull start it. I didn't see where that would make any difference but it did fire up, not instantly but within a few hundred feet. Stopped for breakfast on the way home, fired up instantly.
Wouldn't start the next morning at home.
Put in a new spark plug. Threw a fat blue spark (so did the one I removed). No start.
Unplugged the programmer, same. Adding a battery booster made no difference. Primed the cylinder what I could. Not so much as a pop.
Spark plug doesn't come out wet but the muffler has an odor of fuel.
I'm thinking something is amiss in the cold start section of the brain(?) but am pretty clueless as to what to do next.

I wouldn't classify this as a cold start problem; you said you were out riding for three days, which means that the bike did start cold during some of those days.

I presume no Fault codes are being thrown?

You have already eliminated air and spark as potential problems, so that leaves fuel and compression. Have you ever changed the pump? Can hear the pump priming every time? Go through the diagnostic steps on page 8-39, Code 36 and 50.

After the above, do a compression test to see if you're running low.

Not sure were pages 8-39 are, I have the service manual.
It hasn't thrown a fault code (no warning light flashing).
How do I check compression given the auto compression release?
Am expecting a buddy to arrive and try the pull start deal. It will be a head scratcher if it starts that way again.

Page 8-39 of the Service Manual is what I was referring to.

For compression test go to page 3-9; there is no mention there of auto decompression, so you don't have to worry about it.

This sounds like what happened to my bike at 25000 miles. I think bump starting it turns the motor faster (compared to the starter) to start low compression engines. When the engine is warm all the metal fattens up and make a better seal which in turn boosts compression and it starts easier. I'd say do a compression test then if it low pour some oil into the spark plug hole and try the compression test again. From my experience leads to believe it's the valves.

Running again.
Short version, needed a valve adjustment.
You wouldn't think a retired guy would take so long to get that job done
In my defense I have other bikes to ride and had two long road trips that needed riding.
The two intakes were the tightest, the RH one would barely take the smallest feeler gauge I had (.038, should be .13-.20mm).
So not enough compression when cold?
And when warmed up the aluminum cylinder expands enough to give a bit more clearance and it would start with the button?
Perhaps would have burnt a valve if it had been a tight exhaust but the intakes run a bit cooler?
Anyway, nice to have it back.

So the bike has 38k miles and you had never adjusted the valves before?

That is correct.
Checked them at 18k miles when I bought it.
I'm the third owner (that I know of). Don't know if the PO's adjusted any of them.