Osc Lag when using 3>1 FM

[wireangel]

When using Osc3>Osc 1 FM switch on my XL there is a noticable lad on upward moving voltages when a higher note is first struck. it isn't apparent when playing a note lower than the previous. The pitch also corrects itself rapidly, making subsequent notes correct.
Anyone else noticed this anomaly? I use FM quite a bit and this makes patches annoying/unusable unless you want a slide effect (ie most of the time)!

Side question. When using Osc 1 or 2 as one of the programmable mod sources is that an exp fm source? Manual doesn't specify. Assume it is as freq and waveform adjustments behave as expected.