Thanks for the help!
Both of my serving lines are the same length, and both kegs were "set and forget" over a week to begin with. I tapped one (APA) 4-5 weeks ago, and the second (AIPA) 2-3 weeks ago. One of the most interesting things is that the first (APA) was pouring at a seemingly higher pressure in the beginning, and now it is the second (AIPA). This is what made me wonder if the beer levels had something to do with it (as I mentioned I lost some of the IPA due to leaking). I agree that I don't know why that would be though.
A dip tube length problem isn't some thing that I have thought of, thanks for the suggestion! I haven't noticed any problems with either of these kegs in the past, but maybe while hooking up the serving line I somehow twisted the dip tube so that it is up against the wall at the bottom of the keg? I haven't cut either dip tube. Maybe I'll try turning the line at the ball lock while pouring to see if I notice a difference.
I'd be surprised if either were still fermenting, and creating the pressure. Mostly due to the time that has already gone by, and both having poured at a regular rate at some point. I also typically keep my beers in the primary for a few days after signs of fermentation have stopped and the krausen has dropped.