Within the last two weeks, I had a problem where nothing in my house drained. The bathtub and toilet would drain, but it took hours. I at first thought it was a venting problem, so I climbed up on my roof and flushed the vents. While flushing the vents the level of water in the bathtub increased. I had the local septic company out, and after pumping the septic, they had to snake the main line. They snaked it from the toilet vent on the roof. I watched from the septic tank opening, and saw the clog break free, and open up the main line. Everything drained fine after that.

Fast forward to this morning. While taking a shower the water in the bathtub started backing up. The toilet level went down (not sure if there was bubbling or gurglin), and when it did, the tub drained without any problem.

Any ideas what may be causing this since I just had the main line cleaned?