I am probably imagining this but... I made a new alt a few weeks ago and then ran it's levels up to 5/5/5/4/4 or so, then started timing to POS with various factions. I got POS at Orion for example, in about 45 minutes start to finish. But today I logged on with my regular character and tried getting POS and after a lot MORE missions starting at +800 I was unable to get there with the cargo I had stored.

Is level taken into account for standing increases?

you were not imagining that, I have noticed as well.

you are however imagining the following:

Raindrops on roses and whiskers on kittens
Bright copper kettles and warm woolen mittens
Brown paper packages tied up with strings
These are a few of my favorite things

Cream colored ponies and crisp apple streudels
Doorbells and sleigh bells and schnitzel with noodles
Wild geese that fly with the moon on their wings
These are a few of my favorite things

Girls in white dresses with blue satin sashes
Snowflakes that stay on my nose and eyelashes
Silver white winters that melt into springs
These are a few of my favorite things

When the dog bites
When the bee stings
When I'm feeling sad
I simply remember my favorite things
And then I don't feel so bad

[Repeat all verses]

After having to read that, I'm hoping that the dog is rabid and that you're deathly allergic to bee stings.

D'awww
So sweet it gave me diabetes :3

If I remember correctly, there was some bug with the way faction progresses that makes it harder to get POS standing if you already have high standing. I don't remember the specifics, but I think it had something to do with the amount of faction you gain from completing a given mission decreasing exponentially as you acquire more. So with higher standing, you might get a .01 multiplier on whatever faction you gain, while at lower standing you might only have a .5 multiplier. Thus making it much easier to get POS if you can do it in one shot from low standing all the way to the top, rather than doing multiple missions... or something like that.