No, it is not random. I had no problems for the first several weeks I used them and then I hit a couple of generous lines very hard. Since that point I have tracked it. With technology, they can easily track a particular computer through the cookies that deliver the site to you. Now you can delete the cookies but once you log back in under a "flagged" account they will give an adjusted line.
If you think, it makes perect sense. Again, not bashing them. Their model is to cater to more recreational type bettors. The have a lot of people playing public sides of games, hence they have to adjust the lines. When someone like me comes in and hits a game hard at the advantageous line it is not in their best interest.
Example, yesterday Minnesota was -5 -110 at Bodog when the day began. As players began hitting Minny the line went as high as Minny -6.5 -115. Now I don't how much money moves a line at Bodog but they are obviously getting hit with a fair amount of Minny and do not want to move the lines ot -7 for obvious reasons. Their model is to dish the higher "public line" to their recreational players but yet not get overexposed by their players who are shopping for the best line. Up until 30 minutes before gametime I was being dished Minny -6 -105 and then it finally went to Minny -6 -115. But they did not give me the 6.5 that they had up that you received.
Several other posters have confirmed this practice. Tonights game is the same but i know I will have a good example on one of the primtime games this week. Perhaps if we are logged in at the same time i can show you what I mean.
Nevertheless, best of luck.