can injection spots become unuseable?

I always rotate my injection spots, but can you develope a spot where you have injected too many times and can no longer use? I just did my last injection in my glute, the needle went in fine to a point an then it got a lil tough and it was also hard to inject the oil. There was no blood when I removed the needle and no pain, but a few hours later there was a large blood stain on my boxers. Do I have a scar tissue build up and can no longer inject in my glute? Or does it just need some recovery time an it will be fine? I'm comming off a15 week test e deca cycle, 3 injections a week, but only one injection of test e in each glute per week. Also, not my first cycle.

via World Class Bodybuilding Forum http://www.worldclassbodybuilding.com/forums/f21/can-injection-spots-become-unuseable-133849/