Hey,
Over the last year or so I've made good gains and gotten alot stronger, however, I have stretch marks in the same two places, above my arm pits - they are 2 inch long streeks and seem to have gotten a little longer (since i continue to work out). Right now they are a dark maroon'ish color and about 1/2 cm thick. Is this normal? Should I lay off lifting? Will they stay this dark color forever?

There's quite a few posts on Stretch Marks

In a nutshell, you can minimize the visibility of them but they don't just go away.  Over time, they do blend in a lot and with a tan and such, you hardly notice them.

But to date, there's no 'cure' per se that makes them go away permanently.  Just minimize the visibility and some techniques to avoid getting more.

It's usually associated with fast growth in a particular area.  Around the arm pits (chest area) is very common for a man.