There could be a number of things going on here.
One, bigger, heavier tools are less likely to chatter on their own (ever twang a ruler on your school desk?). With a 1/4 inch gouge, I can't hang out more than 1/2 inch without getting chatter, unless I take half micron dust particle size shavings off. I did see a friend use a thin spindle gouge as a chatter tool to put marks in the lid of a box.
There is always some bumps put in the wood by the difference in how the tool cuts from going through end grain and side grain. If you have noticed, the more you fight it, the worse it gets. Thing here is you do not want a white knuckle grip on the tool. Hold the tool like you would a bird, too tight and you kill it, too loose and it flies away. You also do not want that heavy grip on the tool rest. I find myself more and more now days turning with my left hand on the tool shaft, and not on the tool rest, or barely touching it. You also want a light 'rub' with the bevel. The harder you push on the bevel, the rougher your cuts will be. I saw Mike Mahoney and Stuart Batty turn a bowl together that was 1/8 inch thick, 14 or so wide, and about 8 inches deep. They didn't use a steady rest, or hand support when turning the inside of the bowl. Rubbing the bevel is a very gentle guide, and a touchy/feely thing.
You will get more vibrations when turning the inside of the bowl. Most of the mass has been turned away, and the thin walls of the bowl will flex with tool pressure. Gentle touch.
If you are getting no marks near the bottom and more marks/vibrations near the middle and top, this can again be tool pressure. It can also mean that your bowl is loose in the chuck or on the face plate. With the lathe stopped, give it a hand push check. If it moves at all, tighten things up. The set screws in your chuck can also work loose.
robo hippy