Just a guess here but I'm thinking it is the auto quantize that happens when you record a sequence.
The Sequencer has 64 steps. It automatically puts the notes you play on the nearest 16th or 8th notes. Or, more simply put, it places the notes on the next available step. Try recording something simple in 4/4 using 16ths or 8ths. If the Sequencer plays it back in double time (twice as fast) set the clock division to half of what you have. If it plays back half as slow, double the clock division setting. You are pretty much stuck with timing options they give you. (half, quarter, 8th D, 8th, etc...) Remember, there is no metronome so you are the metronome. Become the metronome.
Hope this helps and doesn't confuse.