First Time using Whirfloc

This is my 4th batch of beer. I decided to make a Moktoberfest. To help clear my wort, I added 1 whirfloc tablet to a 2.5 gallon boil, 15 minutes before flameout. When I racked to my primary, I was sucking up tons of very light floc that did not settle when I waited 10 minutes between cold break and the start of racking. Looking at the bottom of my brew kettle after racking, it seems like there's alot less trub then I've seen in the past.

On a possibly relevant side note, this is the first time I've used Hopunion pellets - the last three batches I used whatever pellets came with the Brewer's Best kits - possibly a cause for the difference?

Did I screw up? Should I re-rack from the primary to get rid of all the nastiness (possible trub) that I sucked up? Should I chill and have another beer although it's almost midnight and i have to wake up at 5am?

You should chill.
You can dump the entiretly of your brew kettle into your fermenter without affecting taste. Anything that was in the brew kettle will settle to the bottom of your fermenter.
On a side note...Any Brewers Best kits I've ever bought have had Hopunion Hops in them.

Whirlfloc basically just coagulates proteins...takes smaller chunks and clumps them into larger chunks. You won't particularly get more proteins setting out before you rack to primary or even during the cold break. Gravity still takes time. The whirlfloc is still working on those really fine particulates even when you are still in primary.

Just be patient with it. You might not notice a difference on brew day, but it does make an overall difference through the complete process on the final product.

I personally use nothing but whirlfloc and a 10-14 day cold crash in the keg during carb/conditioning, and end up with very clear beer.