Not sure if anyone else has seen this yet - Each trace has a pointer at the edge of the screen identifying it as CH1 or CH2. With no signal in, CH2 trace lines up perfectly with CH2 pointer and so the offset reading of the trace (if any) corresponds with the trace position. For CH1 the pointer and the trace are offset by several pixels so the offset reading and the trace position are different. For example the pointer might be offset three divisions and the reading shows 3.00 volts offset but the trace is not directly over the graticule line. This is after the scope has calibrated itself after running about 6 hours. What's more, this offset of CH1 trace varies as you turn CH2 off and on.