Yes, it's L137. I have a pair that I believe are M&F, both around 6". They're great fish.
I also have a large Blue Eye Cochliodon. The 137's eyes are nowhere near that color blue.
The pattern you're seeing is normal, comes and goes. Probably just mood-related. The fins should color up more redish as it settles in, though my two are very different degrees of red.
$65 is a bit high. I've seen them anywhere from $20-$50 at my local shops.
As long as you've got the space just hang onto it and enjoy it. From my experience, they're one of the more active places and seem to get along with everyone.
For those thinking Rhino, I'll be happy to post some pictures of mine if you'd like to see the difference. Rhino is basically all dark brown with some different shade patches, had fairly large scutes on it's side (probably why some call it alligator pleco), and huge flaps on it's nostrils. Another dead giveaway on a rhino it the upper lobe of it's tail is always a light yellow/cream color. Another great and peaceful pleco.