If you didn't change your seat height or tilt, getting lower is likely to put more pressure on your pubic bone and the pubic nerve and artery, which could tip you into numbness, all other things being equal. If you tilt your saddle to far forward, your arms will have to do more work to keep you on the seat. I mean that's just geometry.
Of course, geometry isn't always conclusive. Many Brooks riders tilt the nose up a bit to keep from sliding off without causing numbness....